History
The Jotunheim Beast is native to Jotunheim. It is massive in size and can run at incredible speeds and can even scale surfaces upside down. It can be frozen solid for long periods of time.
Seeing many of his men fall to the Asgardians, the beast was awakened from its deep slumber by Laufey to destroy Thor, Sif, Loki and The Warriors Three (Fandral, Hogun and Volstagg) for intruding in his realm. It was soon killed by Thor, who used the Mjolnir to propell himself through its mouth and blast his way through the backside of its head.[2]
One of these beasts was disturbed by Thor and Malekith's battle through the portals and travelled to London where it rampaged around the city eating Dark Elves and evidently chasing birds.[3]Notes
Due to their primitive nature, bestial traits and allegiance to the Frost Giants, they are sometimes confused with Ice Hounds, though their differences in general size, body structure, hunting tactics and solitary behavior prove they are definitely separate species.