Clyde Langer had his life changed for the worse on 25 June 2007, when Donna Noble turned right instead of left; this small change in affairs produced Donna's World.
Clyde was investigating the Royal Hope Hospital - along with Sarah Jane Smith and his friends, Luke Smith and Maria Jackson - when it was transported to the Moon. (TV: Turn Left) There, the hospital was invaded by Judoon. (TV: Turn Left, Smith and Jones) Clyde died, along with Sarah Jane and his friends, when the hospital ran out of air. (TV: Turn Left)