Mari Collingwood is a fictional character in The Last House on the Left films. She first appears in The Last House on the Left (1972) as a hippie girl abducted on her seventeenth birthday by a fugitive family. Conceptualized by Wes Craven, she was portrayed by a twenty-two-year-old Sandra Peabody in one of her early film appearances. Director Dennis Iliadis brings the character back in the 2009 reimagining, this time portrayed by Sara Paxton.

The Last House on the Left is a 1972 horror film written and directed by Wes Craven in his directorial debut, and produced by Sean S. Cunningham. The film stars Sandra Peabody, Lucy Grantham, David Hess, Fred J. Lincoln, Jeramie Rain, and Marc Sheffler. Additionally, Martin Kove appears in a supporting role. The plot follows Mari Collingwood (Peabody), a teenager who is abducted, raped, and tortured by a family of violent fugitives led by Krug Stillo (Hess) on her seventeenth birthday. When her parents discover what happened to her, they seek vengeance against the family, who have taken shelter at their home.