Chroma
Chroma, full name Chromatic Aberration, is perfectly normal, I swear. It's just a normal person that lives a normal life. It works as a bartender, and lives in an apartment in the city that it can barely afford, even with the roommate. (The roommate is a girl named Alicia.) It also has a cat named Patches. It owns a car, some old rusty shitbox that it never lets anyone borrow for some reason.
It's normal. It has to deal with normal, modern human problems, like not being able to afford rent, or losing its job.
Unfortunately for it, it is also a monster.
It has to eat a human being alive roughly every month, or it will eventually shut down. So, every month, it drives out to some small town, and eats someone alive. It tells everyone it's going stargazing. It coughs up their bones and everything else inedible on the outskirts of town, burns everything flammable, and buries everything else. It prefers not to think about any of this, choosing to block out the faces of its victims with red scribbles.
It feels absolutely awful about all the murder, if it does think about it.