I'll second Bull Shark, Cassowary and The Immortal Jellyfish.
It's page 10 but I'm pretty sure mine is the first nomination for:
Tasmanian Devil
Mongoose
Polar Bear (!!)
Poison Dart Frog
Grizzly Bear
Sun Bear
Great White Shark (!!)
all seconded.
I'll add the cockroach if it hasn't already been nominated - it can survive a Nuclear explosion for god's sake!