Arbok (Japanese: アーボック Arbok) is a Poison-type Pokémon introduced in Generation I. It evolves from Ekans starting at level 22.
Arbok
Cobra
for Cobra in Fictional animals by species
Suggested by caitlinfrost
Obviously, don't nominate any human characters. Hybrids like Cheetah or The Lizard are okay, as are shapeshifters with one set animal form (eg Professor McGonagall.)
