Does Scooby-Doo count? Someone hired an illusionist to make a monster so that they could distract everyone while they set up a robbery. Not a movie but I recently did a Sherlock Holmes Red Headed League arc where the rogues guild wanted to break into a heavily fortified vault but had to get the guy that lived adjacent out. They created an exclusive club that he had been invited to.
Then there's The Thing. A shapeshifting monster that can assume identities of others. Unfortunately the monster can only assume an identity for so long before it needs to switch forms.
I keep thinking I want to run something based on old Godzilla movies, but that would have to involve the PCs also gaining powers of a kaiju temporarily. Maybe something along the lines of Cloverfield where they kaiju is destroying everything in it's patch and the PCs need to fight their way through smaller monsters that it's shedding. Eventually getting to a mecha-kaiju that they have to operate.
