Petesouchi

Petesouchi start life as regular humans, but after adolescence, begin to change into a large crocodile, though retaining their human mind. Like Deep Ones, not all Petesouchi make the change, while others may only partially do so.

In the RPG...

The final crocodile form of a Petesouchi has higher STR, CON, and SIZ than a regular crocodile, but lower DEX and POW. Because they retain their human mind, a Petesouchi has the same INT, whereas a crocodile has no INT at all. The 7e Malleus Monstrorum has increased the range of STR and SIZ, keeping the same averages, while decreasing the range and average of POW.

    Petesouchi have 6-point armour—which means bullets are largely ineffective—but are otherwise fairly simple creatures. Their bite does an average of 10 damage, or it can do a roll which deals 15. The latter has an 88% chance of killing an average human in one go.

In a video game...

The half-formed Petesouchi might make for interesting NPCs, but I doubt there would be a use for the full crocodile form. If people are playing a Call of Cthulhu game, they're going to want to see Mythos creatures, not earthly animals. Sure it's smart, but it can't talk or anything, so it really would just appear to be a large crocodile to a player.

In a film...

The giant crocodile thing has already been done with the Lake Placid films—and you could even argue that they are abnormally intelligent—so I'm not sure there would be much appeal for a Petesouchi.