Universal Studios released both Dracula (1931) and Creature From the Black Lagoon (1954) so having both a vampire and lizardman in the same adventure seems perfectly appropriate.
My CoS GM was less than impressed when I suggested we should run into The Creature in his campaign. Ravenloft is one big homage/rip off of classic horror tropes and I'd have thought The Creature would have fit right in.
He didn't let me play a Monk either. I was hoping for a whole "Legend of the 7 Golden Vampires" type of thing.
I may not have entirely the right mindset for playing CoS, but it has been fun so far.