Margaret Ruth "Margot" Kidder (born October 17, 1948) is a Canadian American actress and activist. She rose to fame in 1978 for her role as Lois Lane in the Superman film series, opposite Christopher Reeve. 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. Her performance as Kathy Lutz in the blockbuster horror film The Amityville Horror (1979) gained her further mainstream exposure. After a highly publicized manic episode and nervous breakdown in 1996, Kidder's career began to slow. By the 2000s, however, she had maintained steady work in independent films as well as television, with guest-starring roles on Smallville, Brothers & Sisters, and The L Word. In 2015, she won an Emmy Award for her performance on the children's television series R.L. Stine's The Haunting Hour. She has also acted in theatrical productions, most notably appearing on Broadway in a 2002 production of The Vagina Monologues. In 2005, Kidder became a naturalized U.S. citizen. She is an outspoken political, environmental, and anti-war activist. She has also advocated the use of orthomolecular medicine, which she credits as having helped treat her bipolar disorder.