10 Video Game Bosses Who Killed Other Bosses

As if one so-called Ultimate Life Form wasn't enough, the final act of Sonic Adventure 2 pulls another one out for you to dig your supersonic quills into - and, of course, it just so happens to be attached to a space station capable of destroying planets.

The Biolizard was created by Dr. Gerald Robotnik, the grandfather of Sonic's archenemy, Dr. Eggman, as a prototype version of what eventually became Shadow the Hedgehog. This beast was abandoned on the space colony ARK for decades, and only when Eggman boots up the space station again does it resurface to cause untold chaos.

Shadow, the true Ultimate Life Form, is fought twice during the Hero campaign, though in the game's final moments, during the Biolizard's second stage as the FinalHazard, he and Sonic form an alliance, using the Chaos Emeralds to defeat the creature in their Super forms.

The fight takes all of Shadow's energy, and he plummets down to Earth, accepting of his fate.

Now, granted, this isn't technically a death, as Shadow is virtually immortal, and, indeed, comes back in the very next main series game, Sonic Heroes. But in Sonic Adventure 2, at least, it's very much treated as one, leading one to believe that his later return may have been something of an unfortunate retcon.