A large fish that comes in many sets. A giant shark comes in Shark Escape and Treasure Trove.
A gray shark appears in Mutiny Isle, nothing much about this shark. (well at least the shark got a small appearance in the Command the crew, rule the seas movie).
A blue Shark appears in Smuggler's fort, later on Smuggler's fort 2.0 the Blue shark got replaced by a crocodile (unbelievable ain't it).
A black Shark appears in the Battle for Treasure island, of course Sharks have black eyes, this one has blue instead of black (and it's indeed the best looking shark, besides the one of Shark escape)
Last, but not least it's the Shark from Shark Escape, he has a spot where the harpoon can be stab to the shark and he has a jaw that can open and close (since the other sharks only have the mouth open).
This is indeed the best shark Mega