Hmm... A howler would be totally cool, but if I can't have that I'd probably pick a Wolverine.
One of the fiercest and most dangerous animals on earth, The wolverine can topple animals as big as Moose and Polar Bear-more than 10 times the Wolverine's size.
The Wolverine is so vicious that Native Americans call it "the evil one". For it's size it is one of the strongest of all mammals(a Wolverine can move a log so heavy it would take two men to lift it). Cougars, lynx, bears, and entire packs of wolves retreat before him in terror and give him their kills. A wolverine was once put in a zoo in the same exhibit as a polar bear, which he promptly killed.
The Wolverine's armory of weapons include; a keen sense of smell and hearing, razor sharp claws,and jaws powerful enough to crack frozen bones to powder and snap large branches with ease(he can even bite the lump from the butt of a rifle).