As hardcore and fiendish as sperm whales and even dolphins can be, the undisputed heavyweight king of the whale world. If you agree and you need a costume for Halloween, then look no further than the Killer Whale Halloween Costume. Killer whales are the mammalian response to the great white shark. It's nature's own little Cold War. It's like the secret turf war between red and grey squirrels, but underwater and awesome as all-get-out. Just ask Pliny the Elder. And that guy knew a thing or two about a thing or two. So take a stand against shark aggression this year by picking up the Killer Whale Halloween Costume. Or, hey, if you don't like killer whales, you can dress up as a false killer whale. Everybody loves a high concept costume, especially marine biologists.