Owen Bywater was the security commander in the Vault, Henry van Statten's underground bunker, in 2012. He was originally from Chicago, though he had Irish ancestry. (PROSE: Dalek) Charged with dealing with the Dalek known as "Metaltron" on its escape from the Cage, he sent one of his officers, De Maggio, on escort detail to ensure Rose Tyler and Adam Mitchell's safety, before engaging in combat — and was the first of the Vault staff to be exterminated by the Dalek's reactivated gunstick. (TV: Dalek)
Rusty the Dalek saw Bywater's death when the Twelfth Doctor and Clara Oswald were in the process of opening up his suppressed memories. (TV: Into the Dalek)