Maureen Forrester (born July 25, 1930) is a Canadian operatic contralto.

She was born Kathleen Stewart in Montreal, Quebec as one of four children. She grew up in a poor section of east Montreal. At age 13, she dropped out of school to help support the family, working as a secretary at Bell Telephone. She was able to pay for voice lessons with Sally Martin, Frank Rowe, and baritone Bernard Daimant. She gave her debut recital at the local YWCA in 1953. Her accompanist was John Newmark, and this was the start of a life-long collaboration. She made her concert debut in Beethoven's Ninth Symphony with the Montreal Symphony Orchestra under Otto Klemperer.

She toured extensively in Canada and Europe with Jeunesses Musicales. She made her New York debut in Town Hall in 1956. Bruno Walter invited her to sing for him; he was looking for the right contralto for a performance and recording of the Mahler Symphony No. 2 "Resurrection." This was the start of a warm relationship with great rapport. Walter had been a student of Mahler, and he trained Forrester in interpretation of his works. She performed at Walter's farewell performances with the New York Philharmonic in 1957.

Forrester became known for her performances of Mahler and for her great stamina, often giving up to 120 performances a year while raising five children. She was considered to have superb German diction and great dramatic sense, which made her a highly-regarded performer of Lieder. She also performed regularly in concert and opera.

Forrester also provided the voice of the Bianca Castafiore character in the television series The Adventures of Tintin.

She has been a champion of Canadian composers, regularly scheduling their works in her programs, especially when she toured abroad. From 1983 to 1988 she served on the Canada Council. In 1967 she was made a Companion of the Order of Canada, and she has been given numerous honorary degrees. She is a member of the Juno Hall of Fame.

In 1986, she published her memoirs, Out of Character (ISBN 0771032285).