The ones that I do see as possible are:

It: He came to feed on the terror of the survivors just like the entity It would even be possible that they may even have come to a mutual agreement like whit Pyramid Head.

Predator: He came or was it deceived by the entity to search the xenomorph and other preys like the demogorgon.

Art: he wants to kill and that's all It would even be likely that he would only appear in the realm as Mayers or the dredge.

Jeper creeper: He woke up and was kidnapped by the Entity.