Mary Katherine Gallagher is a fictional character invented and portrayed by Saturday Night Live cast member Molly Shannon from 1995 to 2001. She was considered the first breakout character from the new 1995 cast, and a significant marker of the increased influence of women writers on the show in the 1990s. Shannon portrayed the character in a 1999 film, Superstar, and she also reprised the role when she hosted Saturday Night Live in 2007.