Margot Kidder is an actress.
Margaret Ruth `` Margot '' Kidder ( born October 17 , 1948 ) is a Canadian American actress and activist . Kidder began her career in the 1960s appearing in low-budget Canadian films and television series , before landing a lead role in Quackser Fortune Has a Cousin in the Bronx ( 1970 ) . She then appeared playing Siamese twins in Brian De Palma 's cult thriller Sisters ( 1973 ) ; in the slasher film Black Christmas ( 1974 ) ; and the drama The Great Waldo Pepper ( 1975 ) , opposite Robert Redford . In 2015 , she won an Emmy Award for her performance on the children 's television series R.L. Stine 's The Haunting Hour . Sisters ( also known as Blood Sisters in the United Kingdom ) is a 1973 American psychological horror film directed by Brian De Palma and starring Margot Kidder , Jennifer Salt and Charles Durning .