Madame Montour (1667 or c. 1685 – c. 1753) was an interpreter, diplomat, and local leader of Algonquin and French Canadian ancestry. Although she was well known, her contemporaries usually referred to her only as "Madame" or "Mrs." Montour. She may have been Isabelle (or Elizabeth) Couc, a mixed born in 1667, or perhaps Isabelle Couc's niece, who was born around 1685 and whose given name is uncertain.

In 1711, Montour began working as an interpreter and diplomatic consultant for the province of New York. Around 1727, she and her husband Carondawana, an Oneida, moved to the province of Pennsylvania. Her village, known as Otstonwakin, was at the mouth of Loyalsock Creek on the West Branch Susquehanna River. The modern borough of Montoursville, named for her, developed on the east bank after the American Revolutionary War.

Montour's son Andrew Montour also became an important interpreter in Pennsylvania and Virginia, as did his son John Montour. Some of Montour's female relatives were prominent local leaders in New York and Pennsylvania, and have often been confused with her by historians.