There could be. But all our physics* implies that any such thing would be unable too interact with us slower-than-light beings. Like, at all, not even in the weakest sense. Then it boils down to the question of what "exists" means; can things "exist" that we cannot, will never, nor could ever in any way detect?

The material/scientific version says no, because either Occam's razor or it not being testable makes it pointless for it. Quite a few religions allow such concepts, though. Same with Science-Fantasy, with parallel universes and all.

*: Which could be completely wrong, we have just found it to be accurate to a very high degree and probability.