Sergei Kozin

"Allow me to introduce: Sergei Kozin, the monster of Magadan!"

- Viktor Reznov to Alex Mason upon first meeting Sergei. "Sergei mugged Dragovich in front of their own people. For his insolence, Dragovich cut out his tongue with a rusted sickle."

- An unused quote explaining Sergei's lack of dialogue.

Sergei Kozin (Russian: Сергей Козин) was a prisoner of the Vorkuta gulag. Nicknamed the "Monster of Magadan," he possessed brute strength, tackling two guards at once and killing them both, killing another guard with a pickaxe uppercut, and body slamming on an armory locker door to crack it open; he also has the hulking build to fit the name; apart from that, little is known of him.

Sergei was seen in the mission "Vorkuta," as part of the band of prisoners who took part in the uprising. He appeared on the way to the elevator, pushed the coal cart with Reznov, and disappeared after he opens the arms locker. He reappeared before the gate to main armory. He used his strength to hold the door open for Mason, Reznov, and the other prisoners, but just as Mason was able to get through, Sergei was shot by one of the guards and the door comes down on top of Sergei, killing him.

Trivia

 * Sergei at one point may have been a resident of Magadan, Russia, this is supported by his nickname, the "Monster of Magadan." It may also hints that he has been a Gulag inmate long before the events in Black Ops since Magadan was known in Russia as the center of the Soviet Gulag system.
 * Prisoners in the Prison Break section of Dead Ops Arcade are based off Sergei, possessing the same character model but have glowing eyes.
 * An image of Sergei and the Vorkuta escape is an optional design for the Playercard.