Dr. Edward Richtofen

"This is Dr. Richtofen, known affectionately as The Butcher to his victims as they scream in agony moments before he snuffs out their light. All through his career, Richtofen has been at the forefront of torture and information extraction research. Richtofen is an incurable sociopath and sees no moral distinction between natural death and murder; the victim is the victim, regardless of how their demise manifests itself." ~ Richtofen's official in-game bio

Dr. Edward Richtofen is the central villain of the Nazi Zombies storyline in the Call of Duty games. He is a sadistic, sociopathic Nazi scientist and professional torturer who is feared even by his own people and was part of the "Group 935" project that created the zombies as assistant to Dr. Ludvig Maxis. Wanting to create an army of undead under his own command, Richtofen betrayed Maxis, who was sane enough to keep his experimentation at a slow pace so as not to start a Zombie Apocalypse, by locking him and his daughter Samantha Maxis in a room with a zombified dog. Maxis himself survived, but committed suicide due to the death of his daughter and his factory subsequently becoming overrun with the zombies.

Richtofen then used a teleporter to escape to Shi No Numa, where he used the kidnapped, physically-enhanced and brainwashed soldiers Tank Dempsey, Nikolai Belinski and Takeo Masaki to help him return to the source of the zombies where he could take control of them by pretending to be just another random survivor like them. Eventually they reached the Moon where the body of Samantha Maxis, who was reborn as the "Announcer" controlling the zombies due to her exposure to Element 115, is, and using the golden rod and magical stone he acquired earlier in the Siberia and Shangri-La levels, releases Samantha from the pyramid she is kept inside of and switches souls with her, becoming the new controller of the zombies and putting Samantha in his own body. It is unknown what happens after this until the next game comes out.