Movie monsters all make the same screechy sound

I swear every alien, dragon, dinosaur, or genetically engineered abomination makes the same sound where it's like a muffled low bellow with a hissing shriek layered on top, and then sometimes they'll give one or both tones a vibrato if they feel like being fancy.

What is it even supposed to be? It doesn't sound like any real animal. It just sounds like you couldn't find a creative sound designer so you got someone to dig through the stock library. It might have been cool back in Attack of the Clones, but now it's honestly just grating and it kills the atmosphere every time I hear it.