[Angrist]

Brontosaurus is funny because it never existed. The name was given to an already named species, Apatosaurus. But apparently nobody can kill the Brontosaurus.

I'm going with the Leviathan here, because a huuuuge monster roaming the oceans sounds cooler than some shy plesiosaur in a tiny lake.
Oh, and the Leviathan would never bother with a single man. It does ships like we open a can of wieners.