Brigadier Sir Alistair Gordon Lethbridge-Stewart, generally referred to simply as the Brigadier, is a fictional character in the British science fiction television series Doctor Who, played by Nicholas Courtney. He is one of the founders of UNIT, an international organization that defends Earth from alien threats, and serves as commander of the British contingent. Almost 20 years after his last appearance, the character returned in the spin-off programme The Sarah Jane Adventures in late 2008. Following Courtney's death in 2011, however, the character of the Brigadier was retired through a line of dialogue in the Doctor Who episode "The Wedding of River Song"; the Doctor is informed by telephone that his old friend died peacefully in his sleep in a nursing home several months earlier. The 2012 episode "The Power of Three" officially introduces the Brigadier's daughter, Kate Stewart, as UNIT's scientific adviser. She was originally introduced in the unlicensed video spin-off Downtime in 1995, in which the Brigadier also appeared, and later played the same role in the fiftieth anniversary episode "The Day of the Doctor".