Kraken
From WikiRaider
The Kraken is a mythical creature found in Norse legends. The latest Tomb Raider Underworld screenshot released by Eidos shows such a kraken sitting in a waterhole in some kind of cave. In the storyboards released by eidos,the way to kill the kraken seem to lure it's tentacles to attatch to a giant cog,then pull it,releasing the spike orb on the monster. It is likely that the kraken will be an enemy faced undirectly,like Tomb Raider 4's creature from the ancient past,where it is required to solve a puzzle to kill the monster.