David (Sleeper)
From Tardis Wiki, the free Doctor Who reference
David was a member of Cell 114, disguised as a human with a wife. When he was activated in 2008, all memories of his former human persona and the morality that went with it were erased. Reverted to a ruthless assassin, he murdered his wife and then Patrick Grainger. He tried to blow up a major military base and killed several soldiers when he attacked it. Captain Jack, Gwen and Beth then tried to stop him and Jack shot him in the shoulder as he was stabbed by David. Although disabled, he refused to be taken alive, and to protect information about Cell 114 from being exposed, he committed suicide. He used his sleeper bomb to kill himself as Jack, Gwen and Beth escaped. (TV: Sleeper)
