Louise Lanctôt, born March 24, 1947 in Montreal, Quebec, Canada, is a convicted terrorist and writer.

A poltical activist for the cause of Quebec independence from Canada, Louise Lanctôt was an active member of the radical Rassemblement pour l'Indépendance Nationale political party that later merged with the Parti Québécois. She was also a member of the Front de Libération du Québec terrorist organization and is the sister of convicted terrorist, Jacques Lanctôt, and was married to Jacques Cossette-Trudel who joined the Front de Libération du Québec with her. She is also referred to as Louise Cossette-Trudel.

The Front de Libération du Québec advocated the use of violence to achieve their goals, calling for a Marxist/anarchist insurrection, the overthrow of the Quebec Government, the separation of Quebec from Canada and the establishment of a workers' society. Members of the Front de Libération du Québec received guerrilla training in selective assassination from Palestinian commandos. From 1963 to 1970, the FLQ committed over 200 violent crimes, including robberies of dynamite, bombings, bank hold-ups, and at least three violent deaths by FLQ bombs and two murders by gunfire.

In 1966 a secret eight-page document entitled "Revolutionary Strategy and the Role of the Avant-Garde" was prepared by the FLQ outlining its long-term strategy of successive waves of robberies, violence, bombings and kidnappings, culminating in insurrection and revolution. A member of the “Liberation Cell,” on October 5, 1970, Louise Lanctôt along with her brother Jacques Lanctôt, Yves Langlois, Nigel Hamer, and Marc Carbonneau put their kidnapping plans into action with the armed abduction of James Cross, the British Trade Commissioner to Canada.

Louise Lanctôt, with the help of her husband and other members of the "Liberation Cell," will hold James Cross hostage, taking his photo and sending it to police with a list of demands that included money and the release of other convicted terrorists. They advise authorities that Cross will be executed and further threats to Cross' life were delivered to several radio stations along with the terrorists demands. This action was followed by a second kidnapping of Quebec Cabinet Minister and Vice-Premier Pierre Laporte by her “Chenier Cell” counterparts. Laporte will be abused by his captors and then executed.

Early in December of 1970, police discovered the location of Louise Lanctôt and her fellow kidnappers holding James Cross. His release was negotiated and on December 3, 1970, Louise Lanctôt with her husband and child, plus the three other terrorists, were granted their request for safe passage to Cuba by the Government of Canada after approval by Fidel Castro. Although Louise Lanctôt and her terrorist friends who wanted to go to Cuba were exiled from Canada for life, they were later found in France. For four years, Louise Lanctôt lived in La Courneuve in Île-de-France.

Over the years, all of the Front de Libération du Québec members wanted to return to Canada and began secret negotiations through the reigning government Parti Québécois to achieve that goal. On October 13, 1977, Quebec Premier René Lévesque announced he was considering a request for a pardon for Louise Lanctôt and her husband. Eventually, the Federal Government consented. On her return to Montreal on December 13, she pled guilty at trial and was sentenced to two years in jail for her part in the kidnapping. She was freed on parole after serving eight months following which she received Quebec government financial assistance to attend the Université du Québec à Montréal where she received a degree in communications in 1982 and continued on to doctoral studies in human sciences.

Divorced from her husband, during the times when the Parti Québécois has been in government, she has been employed by numerous Quebec government funded institutions, including as a researcher for the Collège de Maisonneuve, the Université du Québec à Montréal, Sainte-Justine Hospital, Université de Montréal health administration department, and the "Ordre des infirmières et infirmiers du Québec".

The author of several books, Louise Lanctôt is member of the Quebec Writers Union. She has never apologized for her terrorist acts and although other high-profile separatists such as Pierre Vallières publicly renounced violence, Louise Lanctôt never has.