Margaret Isabel Rideout (née Saunders; June 16, 1923 – May 12, 2010) was a Canadian politician, who represented the electoral district of Westmorland in the House of Commons of Canada from 1964 to 1968. She was the first woman elected to the House of Commons from New Brunswick. She was born June 16, 1923 in the family of Vance and Dolena (McRae) Saunders of Bridgewater N.S. A Liberal, Rideout first won the riding in a 1964 by-election following the death of Sherwood Rideout, her husband and the district's incumbent Member of Parliament.