I will second the following. Now let's Get It On:
Praying Mantis
Inland Taipan
Perentine Goanna
Moose
Poison Dart frog
Australian Box Jellyfish
Mosquito
Bengal Tiger
Wolf
Ursid Bear
Liger
Sun Bear
Dog Whelk
Bull Shark
Immortal Jellyfish
Crown of thorns Jellyfish
Can I nominate the cockroach please? I went to Drusillas this weekend and read that it can survive for ten days without his HEAD. If that's not hard I don't know what is