Blood

Blood is a secret sub-boss who appears at the end of certain fights, born from the corpse of a dead rival, and is a head swap of Hellhound. He is also a member of the Agents of Nekron.

Backstory
Blood was created as a result of an experiment performed by Nekron to create a living robot with all organic components. The result is Blood, a robot made completely from living tissues and organs grown and cultivated within a laboratory. Because of the strange nature of these living organisms, an inordinate amount of blood is needed to keep the creature functioning properly. Blood has been programmed by Nekron to fight and kill and has no mind of his own. He is the only special agent who can withstand a direct transportation jump from Nekron's lair to anywhere on Earth.

Blood, like Shadow, can be found from any background. The difference is Shadow takes you to his world, and Blood is fought on the background you are currently on. To fight Blood, you need to have a perfect round, and then win the match. Note that if you get a Perfect in the first round, Blood will not appear until the match (win 2 out of 3) is over. If you do this, the dead opponent explodes and Blood comes alive! He is all red and has a blob of oozing blood for a head. He also wields the Hand of Death, the same type of Gauntlet that Nekron uses, and therefore a very extended reach. He also shoots fireballs, like Hellhound.