I've made a handful - Mine were created for games so they have unique traits designed for a game system in mind.

One I made are a slime-ish people called Tarbies. They don't naturally have bones so they find/construct their own, they can crack and split in icy weather so they don't live in the cold, and they are born/buried in giant pools where their memories all sort of melt together.

(That last part is a significant problem which they are constantly dealing with)

They're really physically dense and hard to wound unless you hit an internal organ.

They naturally tend to copy people/animals/things that they find interesting which generally creeps people out - This also leads them to being exploited for labor or menial jobs as other races might pretend something is interesting to trick a Tarby into skillfully copying and completing tasks.

Narratively they were designed to be a parallel-ish-design to the setting's robots but alien to just about everyone else.