We just learned about the Arctic Fox.
Don't judge this animal by his size!
The Wolverine is known to be a very ferocious animal,
and even sometimes will try to fight a bear or wolf for food!

(from: wikipedia - wolverine)
The wolverine is also famous.
One of Michigan's nicknames is the Wolverine State and the University of Michigan uses the wolverine as it's mascot because of it's fierce reputation.