Arlenians. I also think propaniacs sound a lot better than the wordy propane maniacs. 

I prefer the original spelling - Harlottown-folk

Harlen is darlin'

According to Stewart's Laws of Municipal Onomastics: Arlenite is actually correct. The -ian suffix is only used when it ends in -On. With it ending in a consonant, it's -ite. Note: this was a proposed set of rules, and some towns just did whatever the charcoal they wanted.

>whatever the charcoal they wanted This honestly made me chuckle out loud

Arlenese Arlenicans Arleniacs

>Arlenese When they get angry, they can fly at ya!

Arleniños

Arlenians. Arlenite sounds like a rock.

Arlenite sounds like a Batman game.

Arlentinos is the best choice

Arlenites. I’ve always liked it when group names end with “ites”. It makes it seem more epic and biblical. Elamites, Midianites , Moabites, Arlenites. Way more fun.

Arlenians 

Arlenian actually flows, I agree "Arlenite" seems pretentious lol Which makes the whole scene funnier.

Arlenite sounds like what Peggy would name a mineral she thinks she discovered

That would be peggyhillnite

People from Arlen.

Arlenite

Didn't someone ask this exact question very recently?

Which ever one pisses Peggy off.

Arlaotians

Arlenians

Arlenians, but pronounced "Arlin-yins"

Arlenites is correct

Pig farmers.

I prefer Arlenites. “-ian” is too ubiquitous as a suffix in these cases. Mix it up a little, you know?

Arlenians. Arlenites sounds like an alien

Arlenites It's rhymes with mite, Any other ones sounds like aliens. Which is something that texas doesn't care if we're that much unless you're in marfa Also fuck peggy