Shelley Marie Hack (born July 6, 1947) is an American model, actress, producer, and political and media advisor. Hack is best remembered for her role as Tiffany Welles in Season 4 (1979–1980) of the ABC television drama Charlie's Angels , replacing the departing Kate Jackson. She appeared in a total of 26 episodes of the series, before being replaced in Season 5 by model-actress Tanya Roberts. Hack's other roles include Cathy Long in Martin Scorsese's film The King of Comedy (1983).