Wolverines

'Wolverines are fast enough to run down a reindeer, strong enough to swim across a river, and agile enough to scale a tree'. National geographical article on the Finnish Wolverine
My son was looking up stuff on the Ekorus - a giant prehistoric mustelid - and it looked a bit like a Wolverine in the picture. The ekorus used to bring down horses and had leopard-like legs so I don't think it is that much like a Wolverine but the Wolverine is an amazing creature. A relative of the weasel that can kill something as large as a moose. Distribution: Canada, Estonia, Finland, Mongolia, Norway, Russia, Sweden, USA Read more here
Wiki on the Wolverine
The Wolverine Foundation site - well worth visiting if you care enough about one the planet's most fascinating creatures.