Fenris Wolf, or simply known as Fenris, is a supporting antagonist in the 2017 Marvel Cinematic Universe film Thor: Ragnarok. She is a ferocious Asgardian wolf who serves as the loyal pet of Hela.
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.)
