http://en.wikipedia.org/wiki/Wolverine
When I was a kid they showed on television a wolverine in a fight with a 10ft grizzly bear. The wolverine sent that bear home running for it's mama.
Mind you the bear weighed over 1,000 lbs and the wolverine all of maybe 20 lbs.
I went to read up on them again and didn't know they could kill a moose.
We were shown pics of wolverines and stuffed wolverines as kids and told if we ever saw one to alert the adults as fast as possible.