Replying to Animal Faceoff! March madness style

In the heat of march madness, and the wandering mind in biology, I decided what do do with my life. When I get old and rich (Assuming I will), my goal is to take the 64 most ferocious animals in the world, have a Safari Selection Sunday to rank them (1-16 seed), and have a tournament bracket style face off. Head to head. They come from four regions: Swamp, Tundra, Desert, Rainforest.
This is like a rip off of that Animal Planet show, but we have no computer simulations here.
What I need now, is 64 fuckin hardcore animals and the winner...
Tiger
Lion
Grizzly Bear
Rhino
Gorilla
Elephant
Anaconda
Jaguar
Hyena
Lemur with a gun
Polar Bear
Crocoldile
Alligator
Cheetah
Wolf
Water Buffalo
Hummingbird
...Keep them coming. My future is at stake here.