Rose-Marie Losier-Cool (born June 18, 1937) is a retired Canadian Senator for New Brunswick.
She was elected the first woman president of the Association des enseignantes et des enseignants francophones du Nouveau-Brunswick in 1983 and has sat on the board of directors of the Canadian Teachers' Federation.
Losier-Cool was appointed to the Senate on March 21, 1995 on the advice of then Prime Minister of Canada Jean Chrétien and sits as a Liberal.
In January 2004, she was appointed Government Whip in the Senate, the first woman ever to hold this role.
Loisier-Cool left the Senate upon reaching the mandatory retirement age of 75 on June 18, 2012.