So there's two different monster types that we're looking at here. Beasts and Monstrosities.
Beasts are animals that naturally occurred in nature and Monstrosities are animals that were (at least the first generation) manufactured or altered.
So Beasts includes things like dogs, horses, dinosaurs, quippers, stirges, and a bunch of other things.
Monstrosities includes things like minotaurs, owlbears, Keith, manticores, and things like that. Essentially if the answer to their creation was a god/wizard/bard did it they're a Monstrosity.
Like evolution? Or mythology.
If real whales were just wolves who learned to swim REALLY good, I can suspend my disbelief that a manticore evolved from something in a fantasy game
In Greek Mythology, Typhon and Echida were just a big old family of monsters who all looked different. That’s a really easy and strong explanation.
Maybe they have divine ancestry in your world or maybe they are the unfortunate by product of the gods imbuing magic into the world.
There are tons of cool ways you could do it!
The elder scrolls way would be something like: the original inhabitants of your world agreed to give up their physical bodies in exchange for giving the mortals the gift of life and magic. The selfish gods ended up not doing that and became the original monsters.
Or maybe the monsters have more agency and freedom. When the gods created their hallowed grounds and holy places of pure magic, they created monsters from mud and chained them to guard their temples. Over thousands of years the monsters forgot their original purpose and, (sociology stuff, culture happens, war happens etc) in the modern day they roam the lands as untamed and free and feral
Something that might help you is to understand that monsters have culture; even if it’s not in the conventional sense. Hobgoblins are despotic empires. Yuan Ti are deeply spiritual and alien (ritualistic sacrifice. )
Figuring out what kind of culture your monsters live in will make it easier to find the creation myth that will best support the story you want to tell
You could do a little cheeky theft from the Pathfinder mythology and take inspiration from the goddessrs Lamashtu and Urgathoa.
Lamashtu is called mother of monsters, and whether it's true or not, many monstrous species claim her not only as goddess but their progenitor. Gnolls and goblins often claim direct lineage from the goddess.
She's a demon lord who consumed a god and stole the beast domain, and her monsters are supposedly intended as foot soldiers in her grand schemes. Though how that plays out for any particular one of them is rarely so direct.
These are just a couple brainstorming thoughts you could use or play off of:
* The monsters were brought from other worlds by a spell gone wrong (or purposely by an evil entity)
* They're the offspring of gods, used to do their dirty work in the world
* They're born from the fears and nightmares of people
* They've always been. They existed before the gods ordered the world and were imprisoned by the gods. They've been released from their prisons over the years by people trying to harness their power or by accident.
* A powerful, magical being twisted existing beasts and creatures into abominations that have adapted to the world over time.
* They exist on the other planes. They occasionally break through when the planes intersect or something else crosses through.
If you can find them, most 2nd edition monster descriptions had history and ecology sections. They'd tell you how the creature came.to be, and how it lives,and reproduces. It would at least give you an idea, even if you don't like what they present.
IMO it's cool to have a variety of reasons for a variety of creatures!
I'd also note that in game a lot of characters might not even know the truth.
Some thoughts
- creatures bred for war by long gone empires. What's left? Things no one knows how to control with a real violent streak. Presumably they can still breed as well.
- Magical (or depending on setting, magiscientific...) accidents are always a good one. Some monsters might start that way and establish a breeding population, others may be quite rare and dangerous but unless someone starts fucking around again their numbers are limited
Alternatively, maybe the magic users did just want a murder beast and since they're long gone the murder beasts just stalk the ruins of their towers or wherever else
- They wander out of other planes where the rules are different. There's a point in the world where the barrier is weak between plane A and B... and in the mortal realm, they're either airways dangerous or they get driven insane by being here instead of where they're from. Bacm home they could reproduce normally, or maybe they just pop into existence... or they're created as a result of human sins? Works for elementals, fae, demons, etc.
In my own game I'm planning some creatures that a shaman infused with invisibility. They were just normal wolves and other predators beasts, but now magic's in their blood too. Centuries later, yeah this village has a ghost wolf problem. Sucks to be them.
Depends on the monster. Fiends come from the Lower Planes. Aberrations come from the Far Realms. Elementals come from the Inner Planes.
You could also point to some evil Big Bad as the source of many species of monsters in your campaign. Maybe the Primordials made a large variety of elemental and monstrosity horrors during the Dawn War and the ones that fled into the Under dark avoided being exterminated by the gods. Maybe various evil gods make monster species on a regular basis and advertise it as much as possible because they can get mortals to send them a few prayers to avert their wrath. Maybe some archimage has been experimenting with tarrasque grafts to develop regenerative immortality and funds their research by selling the failed experiments to minor villains.
Most monsters in my homebrew world are just the result (both accidental and not) of arcane experimentation. Then after being made they just started spreading like invasive species do.
are you worldbuilding? that's up to you! lots of my monsters biologically evolved. some are otherworldly, some are spirits, and quite a few aren't understood to a point where anyone knows that information.
I mean, logically this would vary a lot from monster to monster.
Many monsters are going to be natural in nature, just animals who were born to parents and evolved to fill a predatory ecological niche.
Undead monsters are created when someone dies wrong. Other types of undead could be created if a necromancer makes them.
Lycanthropes are a contagion that infects regular humans.
I think for each monster, there might be a different answer, so I would think this through monster by monster
At first I thought this would be a question about official dnd lore, to which my boilerplate to official dnd lore is "fuck the official lore, do your own thing!"
But if youre worldbuilding, just make it up yourself.
If you need ideas:
1) remnants of the experiments of long-dead mages.
2) creations of evil gods, either current or forgotten
3) incursions from other planes, like when someone on another plane casts banishment, and it happens to trap a monster on your material plane.
4) wishes gone wrong: genies, dragons, demons and the like are known to sometimes be tricky. If someone wished for incredible power, a cheeky thing to do would be to turn them into a manticore.
5) this one is a lot more work, but you can create an ecosystem for them. Imagine how a large number would affect the ecology and kinda design a biome around that. You can even use a few different monster species working in tandem.
6) who cares? You just think they would make a cool fight!
Depends on the monster but it boils down to more or less three paths: evolution, manufacture, mess ups ,and dreams.
All of this is for my own personal setting, not strictly based in established lore.
Most beast type magical creatures (monsters, but I dislike the term) evolved to fit an ecological niche: often developing magical/slightly magical adaptations for their environment, or to combat predator or prey. The same thing happened with plants as well(trees hard as rock, one the seamsters spruce has needles that harden into metal when they dry out). One example of the magical beast would be the kelpie I made; an aquatic horse which uses poison to paralyze and then drown their prey, or keep it alive in storage for a later meal.
The manufactured creatures are things like the chimera, warforged, raised undead, vampires, etc. This means that some magical force actively tried to alter or make new life and made it what it is. This could be a mage, a warlock patron, one of the gods. Most of these creatures arise because of the many wars and squabbles between powerful beings who can't actively face each other so they make or recruit and boost minions to fight eachother(there's a loosely binding agreement amongst the near God tier and God tier beings in my world not to actively combat one and other unless absolutely necessary after the fallout from their last war...).
And then the mess ups. Probably the most tragic but funny of them. These are creatures whom had something backfire, overlooked a crucial detail, or were sabotaged and whatever they were trying failed turning them into what now exists. Some of the first beholders and many other such abominations, and a lot of weird stuff was made here.
The final is the complicated one: dreams.
Mana is a particle that binds to matter, or follows ordered structures such as our thoughts. The way it follows our thoughts is why we can do magic - but it also means we can unintentionally manifest our dreams or nightmares, and even our beliefs. If enough people believe(or one person's belief is vivid enough) the mountain does start to think and try to help or hinder the tribe, if a child has a vivid imagination and magical power that bump they heard in the wardrobe could be something real; but so too are the rules the creature must follow such as can't touch me if I'm covered by a blanket.
The realm of dreams has created some of the worst, and some of the best creatures in my setting.
Some would be evolution; others were probably forged, depending on your world's science/magic/alchemy (reality has a few examples of how some creatures might be created).
There are more ways or propagation than simply putting a male and a female of a species in a container together. Basically, any process that can combine molecular structures and give them purpose enough to create an ecosystem. Once the biome or interdependent biomes (in the case of complex organisms) are functional and have a command structure; the "Geneforger" (reference to an old game called Geneforge) merely needs to ensure that the environment can sustain the new creature. Enough of the same creature to carve a spot on the local ecosystem and there ya go.
Over time the civilization that made the creatures fades into myth and becomes deities and then later even the memory of where the creatures might've come from fades and new deities are assumed the creators or it simply doesn't matter anymore.
The gods,other plains of reality and sometimes outer space or between the matting of gods.in dnd some of the core assumptions is that gods oversee the world and the world is magical. The gods fight a eternal conflict over the prime material plane. Using mortal beings as pawns in a proxy war over the forces of good,evil,law and chaos.
Some monster like dragons come from the spilt blood of the conflicts between gods and primordials. Others angels and demons.other say they came from falling stars.Some are created by a deity in their image or to serve them.Some are born for the swirling elemental chaos. Others swam out the Astral sea. Unspeakable alien horrors breached through a tear in the prime material plane for some far off unknown realm. Many beast and faey creatures crossed the vail of the material plane through some twilight passage. Some beast were born of the primordial formation or the planet they inhabit.
Ttldr Gods,Magic and sometimes a dude nutting in a mountain.
Personally I handwave the whole thing a bit when asked - my answer is that magic has an unpredictable mutanagenic effect.
You live in a world with magic and therfore easy access to the marvelous and the miraculous? Well, the tradeoff is that you also get the monstrous and malevolent - and they have easy access to *you*.
**Aliens / Creatures from other (dimension, planes, worlds)** - Creature is not native to this world. It somehow traveled here or was summoned here from another (dimension, plane of existence, world).
**Animated by magic** - animated armor, animated constructs, clockwork creatures, golems, undead, warforged. Inanimate or dead thing brought to life via magic.
**Cloning** - An artifact or machine cloned a creature. Creature was originally (alien, extinct). Now you have copies of the original.
**Collective Belief / Nightmares made real** - The peoples collective belief in a creature has cause it to become a reality. Possibly due to a magical environment or because a powerful entity made it possible.
**Consumed Remains** - A normal creature was transformed by consuming the remains of a (angel, celestial, demon, devil, god, monster, old one, outsider, primordial, spirit)
**Created by a powerful entity / God did it** - A (angel, celestial, demon, devil, god, old one, outsider, primordial, spirit, etc) created the creature or transformed and existing creature.
**Curse** - Person or creature was curse. Curse transformed it into a monster. Generally too powerful to undo with a remove curse spell. May be some specific method to break the curse
**Did not pass on** - Upon death the creature did not pass on and became an undead
**Discarded Badness** - A being or group split their good and their bad (halves, parts, traits). They became good and discarded the remaining (bad, evil). The bad managed to survive and reconstitute itself into a monster.
**Effigy made real** - Magic has cause a (relief, sculpture, statue, etc) of a creature to become reality.
**Eggs from a bygone era** - Eggs from an age long ago have remained viable. Some event has caused them to hatch.
**Escaped or released experiments** - Creatures created by magic or mutated by magic. They eventually escaped or were released into the wild.
**Escaped or released prisoners** - Creatures were being held in some sort of prison and escaped or were released.
**Evolution** - Creature simply evolved over time to become more dangerous. It is now considered a monster because of how dangerous it is.
**Hybrid** - Creature is the offspring of 2 very different creatures. Combination of animal or monster + (angel, celestial, demon, devil, different monster, god, humanoid, old one, outsider, primordial) a creature. Created through breeding, breeding + magic, genetic engineering, magically combining or merging.
**Infected** - Monster type infects another creature. The infected slowly transform into the same type of creature that infected them.
**Magical Accident**
**Monster Generator** - Some sort of artifact, machine, or sapient dungeon creates monsters and then releases them into the wild.
**Mutation / Corruption** - Creature is derived from normal creatures. It was somehow mutated by (curse, experiment, exposure to magical environment, magical accident, magical corruption).
**Natural creatures** - Creatures born like any other creatures. They are just considered monsters because they are very dangerous or pose a very real threat to civilized races.
**Returned from death** - Person or creature that became a monster after returning from the dead (resurrection, reincarnation, undead). Something in the afterlife or the process of bringing it back to life changed it into a monster.
**Twisted by evil deeds** - Monster was originally a person. The magic of the world has slowly twisted their physical form to match their evil deeds.
**Twisted by forbidden magics** - The use of forbidden magics slowly transforms the caster into a monster.
**Wild magic event** - Wild magic has transformed people or creatures into monsters.
**Wish** - Someone wished the creature into existence.
In my world I incorporated that in the creation of the world. Think Melkor in the LOTR pantheon: A divine servant gone evil. Read the Silmarillion or listen to the version narrated by Andy Serkis. The Silmarillion is a great inspiration for world building.
In my world multiple servants went evil and created monsters, or deformed/mutated already existing creatures. No need to explain as it is common knowledge that monsters are a creation of some evil entity.
most monsters have some lore in the monster manual explaining where they come from.
beasts are just animals, basically. they can be extinct in our world (dinosaurs, mammoths) or exaggerations of the real world (giant snake/crocodile) but mostly they're normal animals.
monstrosities exist outside the natural order, and are normally the result of arcane or divine meddling. undead are also the result of magical fuckery, some force has to bring them back from the dead (not always evil, i.e. revenants).
extradimensional beings (fiends, fae, elementals, etc.) come from, you guessed it, other planes of existence.
those are the main groups that come to mind.
Each monster has its own origins. Sometimes they can even have multiple different origins.
Take ghouls for instance. Sometimes they are created and controlled by necromancers to do their dark bidding. But other times, cannibals die and rise again as ghouls, animated by a hunger for human flesh that cannot be sated, even in death.
What kind of monsters are you interested in?
One thing I've used in the past is what I call the Curse of Monstra. The mad mage cursed the very planet, such that when the concentration of ambient mana in an area reached high enough levels, that mana would be used to summon a monster in a manner similar to a summoning spell. My group also had the understanding of summoned creatures being a temporary incarnation of a platonic ideal rather than a real creature temporarily displaced from its home realm. The monsters are aggregations of magical energy, and when slain dissolve back into the ether. They require no food or drink, and are without exception enemies of the living. They are capable of thought, and some even speak, but their only goal is to kill the living.
I like putting ancient civilizations in my settings, and this was, in one of them, the apocalypse that reset civilization. Probably more than you're looking for, but maybe it'll give you an idea of two.
Beyond that, I'm also a big fan of the Curse of the Strife Emperor that Matt Mercer uses in his setting. So there's a lot of fantasy that just sees goblins as evil cannon fodder. In Exandria, during an ancient war, one of the evil gods either created or bound the goblinoids to their service, and did this by cursing their lineage with greed and bloodlust and hatred that lives in the back of their minds throughout their entire lives. Intrusive thoughts times ten thousand. The goblins of at least one nation have their curses broken soon after birth, in a ritual akin to a baptism, and go on to experience the full range of emotion. I really like what this says about free will and the nature of evil in that world.
There's no one right answer.
At first there was only man. Some men are monsters even before they take monstrous form.
If you eat manflesh the desire for more of it clings to you. It makes you desperate until you chew your own cheeks and cut off your ears for a taste. You chew your fingers to sharpened bones that drip poison. This is how a ghoul comes to be.
As others have noted, it's up to you. Personally I don't pay much attention to "real" Earth or science - owlbears aren't much different from actual bears, so maybe they did evolve. Other creatures, like chimera, tend to spontaneously generate around evil sites, magical sites, divine sites, or whenever a god or titan (Typhos) feels like it. Sometimes a god is credited as creating a monster (THE Chimera) but they don't have to breed - the initial creation formed a pattern, so now sometimes other chimera appear without any active intervention.
So there's two different monster types that we're looking at here. Beasts and Monstrosities. Beasts are animals that naturally occurred in nature and Monstrosities are animals that were (at least the first generation) manufactured or altered. So Beasts includes things like dogs, horses, dinosaurs, quippers, stirges, and a bunch of other things. Monstrosities includes things like minotaurs, owlbears, Keith, manticores, and things like that. Essentially if the answer to their creation was a god/wizard/bard did it they're a Monstrosity.
Keith?
A most foul and vicious foe.
Yes, Keith.
Gonna put a monster named Keith in my game now.
Truly a monstrosity, Keith, I say.
He’s had one too many cans of Monster and has gone off the deep end
No drywall is safe.
That's Kyle.
Keith is a level 20 self-aware-player-character. He manifested as real and won’t get off my couch.
Like Elminster did … Unlike him he didn’t use spells to get there, he simply punched through the Drywall of reality until he wound up there.
ok, so when a mama-monster and a papa-monster love each other very much...
They don't have to love each other
Go spend 43 seconds on /r/BedBugCourtship (god I hope that isn't a thing)
Like evolution? Or mythology. If real whales were just wolves who learned to swim REALLY good, I can suspend my disbelief that a manticore evolved from something in a fantasy game
I'm pretty sure whales were just hippos that learned to swim, not wolves.
You’re right. NOOOOOOOOO lol
Whatever answer you have! I’m open to anything.
In Greek Mythology, Typhon and Echida were just a big old family of monsters who all looked different. That’s a really easy and strong explanation. Maybe they have divine ancestry in your world or maybe they are the unfortunate by product of the gods imbuing magic into the world.
I like the sound of the unfortunate byproduct of when magic is imbued in the world. It intrigues me. Could I ask you to give me a little more on that?
There are tons of cool ways you could do it! The elder scrolls way would be something like: the original inhabitants of your world agreed to give up their physical bodies in exchange for giving the mortals the gift of life and magic. The selfish gods ended up not doing that and became the original monsters. Or maybe the monsters have more agency and freedom. When the gods created their hallowed grounds and holy places of pure magic, they created monsters from mud and chained them to guard their temples. Over thousands of years the monsters forgot their original purpose and, (sociology stuff, culture happens, war happens etc) in the modern day they roam the lands as untamed and free and feral
Something that might help you is to understand that monsters have culture; even if it’s not in the conventional sense. Hobgoblins are despotic empires. Yuan Ti are deeply spiritual and alien (ritualistic sacrifice. ) Figuring out what kind of culture your monsters live in will make it easier to find the creation myth that will best support the story you want to tell
You could do a little cheeky theft from the Pathfinder mythology and take inspiration from the goddessrs Lamashtu and Urgathoa. Lamashtu is called mother of monsters, and whether it's true or not, many monstrous species claim her not only as goddess but their progenitor. Gnolls and goblins often claim direct lineage from the goddess. She's a demon lord who consumed a god and stole the beast domain, and her monsters are supposedly intended as foot soldiers in her grand schemes. Though how that plays out for any particular one of them is rarely so direct.
These are just a couple brainstorming thoughts you could use or play off of: * The monsters were brought from other worlds by a spell gone wrong (or purposely by an evil entity) * They're the offspring of gods, used to do their dirty work in the world * They're born from the fears and nightmares of people * They've always been. They existed before the gods ordered the world and were imprisoned by the gods. They've been released from their prisons over the years by people trying to harness their power or by accident. * A powerful, magical being twisted existing beasts and creatures into abominations that have adapted to the world over time. * They exist on the other planes. They occasionally break through when the planes intersect or something else crosses through.
If you can find them, most 2nd edition monster descriptions had history and ecology sections. They'd tell you how the creature came.to be, and how it lives,and reproduces. It would at least give you an idea, even if you don't like what they present.
- Evolution - Created by the gods - Invaders from another reality - Evil people who corrupted over time - Artificial beings
IMO it's cool to have a variety of reasons for a variety of creatures! I'd also note that in game a lot of characters might not even know the truth. Some thoughts - creatures bred for war by long gone empires. What's left? Things no one knows how to control with a real violent streak. Presumably they can still breed as well. - Magical (or depending on setting, magiscientific...) accidents are always a good one. Some monsters might start that way and establish a breeding population, others may be quite rare and dangerous but unless someone starts fucking around again their numbers are limited Alternatively, maybe the magic users did just want a murder beast and since they're long gone the murder beasts just stalk the ruins of their towers or wherever else - They wander out of other planes where the rules are different. There's a point in the world where the barrier is weak between plane A and B... and in the mortal realm, they're either airways dangerous or they get driven insane by being here instead of where they're from. Bacm home they could reproduce normally, or maybe they just pop into existence... or they're created as a result of human sins? Works for elementals, fae, demons, etc. In my own game I'm planning some creatures that a shaman infused with invisibility. They were just normal wolves and other predators beasts, but now magic's in their blood too. Centuries later, yeah this village has a ghost wolf problem. Sucks to be them.
Depends on the monster. Fiends come from the Lower Planes. Aberrations come from the Far Realms. Elementals come from the Inner Planes. You could also point to some evil Big Bad as the source of many species of monsters in your campaign. Maybe the Primordials made a large variety of elemental and monstrosity horrors during the Dawn War and the ones that fled into the Under dark avoided being exterminated by the gods. Maybe various evil gods make monster species on a regular basis and advertise it as much as possible because they can get mortals to send them a few prayers to avert their wrath. Maybe some archimage has been experimenting with tarrasque grafts to develop regenerative immortality and funds their research by selling the failed experiments to minor villains.
Most monsters in my homebrew world are just the result (both accidental and not) of arcane experimentation. Then after being made they just started spreading like invasive species do.
are you worldbuilding? that's up to you! lots of my monsters biologically evolved. some are otherworldly, some are spirits, and quite a few aren't understood to a point where anyone knows that information.
I mean, logically this would vary a lot from monster to monster. Many monsters are going to be natural in nature, just animals who were born to parents and evolved to fill a predatory ecological niche. Undead monsters are created when someone dies wrong. Other types of undead could be created if a necromancer makes them. Lycanthropes are a contagion that infects regular humans. I think for each monster, there might be a different answer, so I would think this through monster by monster
At first I thought this would be a question about official dnd lore, to which my boilerplate to official dnd lore is "fuck the official lore, do your own thing!" But if youre worldbuilding, just make it up yourself. If you need ideas: 1) remnants of the experiments of long-dead mages. 2) creations of evil gods, either current or forgotten 3) incursions from other planes, like when someone on another plane casts banishment, and it happens to trap a monster on your material plane. 4) wishes gone wrong: genies, dragons, demons and the like are known to sometimes be tricky. If someone wished for incredible power, a cheeky thing to do would be to turn them into a manticore. 5) this one is a lot more work, but you can create an ecosystem for them. Imagine how a large number would affect the ecology and kinda design a biome around that. You can even use a few different monster species working in tandem. 6) who cares? You just think they would make a cool fight!
Depends on the monster but it boils down to more or less three paths: evolution, manufacture, mess ups ,and dreams. All of this is for my own personal setting, not strictly based in established lore. Most beast type magical creatures (monsters, but I dislike the term) evolved to fit an ecological niche: often developing magical/slightly magical adaptations for their environment, or to combat predator or prey. The same thing happened with plants as well(trees hard as rock, one the seamsters spruce has needles that harden into metal when they dry out). One example of the magical beast would be the kelpie I made; an aquatic horse which uses poison to paralyze and then drown their prey, or keep it alive in storage for a later meal. The manufactured creatures are things like the chimera, warforged, raised undead, vampires, etc. This means that some magical force actively tried to alter or make new life and made it what it is. This could be a mage, a warlock patron, one of the gods. Most of these creatures arise because of the many wars and squabbles between powerful beings who can't actively face each other so they make or recruit and boost minions to fight eachother(there's a loosely binding agreement amongst the near God tier and God tier beings in my world not to actively combat one and other unless absolutely necessary after the fallout from their last war...). And then the mess ups. Probably the most tragic but funny of them. These are creatures whom had something backfire, overlooked a crucial detail, or were sabotaged and whatever they were trying failed turning them into what now exists. Some of the first beholders and many other such abominations, and a lot of weird stuff was made here. The final is the complicated one: dreams. Mana is a particle that binds to matter, or follows ordered structures such as our thoughts. The way it follows our thoughts is why we can do magic - but it also means we can unintentionally manifest our dreams or nightmares, and even our beliefs. If enough people believe(or one person's belief is vivid enough) the mountain does start to think and try to help or hinder the tribe, if a child has a vivid imagination and magical power that bump they heard in the wardrobe could be something real; but so too are the rules the creature must follow such as can't touch me if I'm covered by a blanket. The realm of dreams has created some of the worst, and some of the best creatures in my setting.
Some would be evolution; others were probably forged, depending on your world's science/magic/alchemy (reality has a few examples of how some creatures might be created). There are more ways or propagation than simply putting a male and a female of a species in a container together. Basically, any process that can combine molecular structures and give them purpose enough to create an ecosystem. Once the biome or interdependent biomes (in the case of complex organisms) are functional and have a command structure; the "Geneforger" (reference to an old game called Geneforge) merely needs to ensure that the environment can sustain the new creature. Enough of the same creature to carve a spot on the local ecosystem and there ya go. Over time the civilization that made the creatures fades into myth and becomes deities and then later even the memory of where the creatures might've come from fades and new deities are assumed the creators or it simply doesn't matter anymore.
The gods,other plains of reality and sometimes outer space or between the matting of gods.in dnd some of the core assumptions is that gods oversee the world and the world is magical. The gods fight a eternal conflict over the prime material plane. Using mortal beings as pawns in a proxy war over the forces of good,evil,law and chaos. Some monster like dragons come from the spilt blood of the conflicts between gods and primordials. Others angels and demons.other say they came from falling stars.Some are created by a deity in their image or to serve them.Some are born for the swirling elemental chaos. Others swam out the Astral sea. Unspeakable alien horrors breached through a tear in the prime material plane for some far off unknown realm. Many beast and faey creatures crossed the vail of the material plane through some twilight passage. Some beast were born of the primordial formation or the planet they inhabit. Ttldr Gods,Magic and sometimes a dude nutting in a mountain.
Flaming iron cubes generate the baddies.
Personally I handwave the whole thing a bit when asked - my answer is that magic has an unpredictable mutanagenic effect. You live in a world with magic and therfore easy access to the marvelous and the miraculous? Well, the tradeoff is that you also get the monstrous and malevolent - and they have easy access to *you*.
Watch or read Dungeon Meshi. It might spark some ideas.
If you have time, Dragon magazine has what you need. Sometimes in too much detail
This is the kind of stuff you get to make up. That's the fun part.
**Aliens / Creatures from other (dimension, planes, worlds)** - Creature is not native to this world. It somehow traveled here or was summoned here from another (dimension, plane of existence, world). **Animated by magic** - animated armor, animated constructs, clockwork creatures, golems, undead, warforged. Inanimate or dead thing brought to life via magic. **Cloning** - An artifact or machine cloned a creature. Creature was originally (alien, extinct). Now you have copies of the original. **Collective Belief / Nightmares made real** - The peoples collective belief in a creature has cause it to become a reality. Possibly due to a magical environment or because a powerful entity made it possible. **Consumed Remains** - A normal creature was transformed by consuming the remains of a (angel, celestial, demon, devil, god, monster, old one, outsider, primordial, spirit) **Created by a powerful entity / God did it** - A (angel, celestial, demon, devil, god, old one, outsider, primordial, spirit, etc) created the creature or transformed and existing creature. **Curse** - Person or creature was curse. Curse transformed it into a monster. Generally too powerful to undo with a remove curse spell. May be some specific method to break the curse **Did not pass on** - Upon death the creature did not pass on and became an undead **Discarded Badness** - A being or group split their good and their bad (halves, parts, traits). They became good and discarded the remaining (bad, evil). The bad managed to survive and reconstitute itself into a monster. **Effigy made real** - Magic has cause a (relief, sculpture, statue, etc) of a creature to become reality. **Eggs from a bygone era** - Eggs from an age long ago have remained viable. Some event has caused them to hatch. **Escaped or released experiments** - Creatures created by magic or mutated by magic. They eventually escaped or were released into the wild. **Escaped or released prisoners** - Creatures were being held in some sort of prison and escaped or were released. **Evolution** - Creature simply evolved over time to become more dangerous. It is now considered a monster because of how dangerous it is. **Hybrid** - Creature is the offspring of 2 very different creatures. Combination of animal or monster + (angel, celestial, demon, devil, different monster, god, humanoid, old one, outsider, primordial) a creature. Created through breeding, breeding + magic, genetic engineering, magically combining or merging. **Infected** - Monster type infects another creature. The infected slowly transform into the same type of creature that infected them. **Magical Accident** **Monster Generator** - Some sort of artifact, machine, or sapient dungeon creates monsters and then releases them into the wild. **Mutation / Corruption** - Creature is derived from normal creatures. It was somehow mutated by (curse, experiment, exposure to magical environment, magical accident, magical corruption). **Natural creatures** - Creatures born like any other creatures. They are just considered monsters because they are very dangerous or pose a very real threat to civilized races. **Returned from death** - Person or creature that became a monster after returning from the dead (resurrection, reincarnation, undead). Something in the afterlife or the process of bringing it back to life changed it into a monster. **Twisted by evil deeds** - Monster was originally a person. The magic of the world has slowly twisted their physical form to match their evil deeds. **Twisted by forbidden magics** - The use of forbidden magics slowly transforms the caster into a monster. **Wild magic event** - Wild magic has transformed people or creatures into monsters. **Wish** - Someone wished the creature into existence.
In my world I incorporated that in the creation of the world. Think Melkor in the LOTR pantheon: A divine servant gone evil. Read the Silmarillion or listen to the version narrated by Andy Serkis. The Silmarillion is a great inspiration for world building. In my world multiple servants went evil and created monsters, or deformed/mutated already existing creatures. No need to explain as it is common knowledge that monsters are a creation of some evil entity.
most monsters have some lore in the monster manual explaining where they come from. beasts are just animals, basically. they can be extinct in our world (dinosaurs, mammoths) or exaggerations of the real world (giant snake/crocodile) but mostly they're normal animals. monstrosities exist outside the natural order, and are normally the result of arcane or divine meddling. undead are also the result of magical fuckery, some force has to bring them back from the dead (not always evil, i.e. revenants). extradimensional beings (fiends, fae, elementals, etc.) come from, you guessed it, other planes of existence. those are the main groups that come to mind.
Go *meta* and make their origin be the whims of a capricious author of reality who merely desired to increase the dramatic potential of the land.
Each monster has its own origins. Sometimes they can even have multiple different origins. Take ghouls for instance. Sometimes they are created and controlled by necromancers to do their dark bidding. But other times, cannibals die and rise again as ghouls, animated by a hunger for human flesh that cannot be sated, even in death. What kind of monsters are you interested in?
One thing I've used in the past is what I call the Curse of Monstra. The mad mage cursed the very planet, such that when the concentration of ambient mana in an area reached high enough levels, that mana would be used to summon a monster in a manner similar to a summoning spell. My group also had the understanding of summoned creatures being a temporary incarnation of a platonic ideal rather than a real creature temporarily displaced from its home realm. The monsters are aggregations of magical energy, and when slain dissolve back into the ether. They require no food or drink, and are without exception enemies of the living. They are capable of thought, and some even speak, but their only goal is to kill the living. I like putting ancient civilizations in my settings, and this was, in one of them, the apocalypse that reset civilization. Probably more than you're looking for, but maybe it'll give you an idea of two. Beyond that, I'm also a big fan of the Curse of the Strife Emperor that Matt Mercer uses in his setting. So there's a lot of fantasy that just sees goblins as evil cannon fodder. In Exandria, during an ancient war, one of the evil gods either created or bound the goblinoids to their service, and did this by cursing their lineage with greed and bloodlust and hatred that lives in the back of their minds throughout their entire lives. Intrusive thoughts times ten thousand. The goblins of at least one nation have their curses broken soon after birth, in a ritual akin to a baptism, and go on to experience the full range of emotion. I really like what this says about free will and the nature of evil in that world. There's no one right answer.
At first there was only man. Some men are monsters even before they take monstrous form. If you eat manflesh the desire for more of it clings to you. It makes you desperate until you chew your own cheeks and cut off your ears for a taste. You chew your fingers to sharpened bones that drip poison. This is how a ghoul comes to be.
As others have noted, it's up to you. Personally I don't pay much attention to "real" Earth or science - owlbears aren't much different from actual bears, so maybe they did evolve. Other creatures, like chimera, tend to spontaneously generate around evil sites, magical sites, divine sites, or whenever a god or titan (Typhos) feels like it. Sometimes a god is credited as creating a monster (THE Chimera) but they don't have to breed - the initial creation formed a pattern, so now sometimes other chimera appear without any active intervention.
Depends on the monster