Sarah Margaret Armour Robertson (1891–1948) was a Canadian painter known for her landscapes, still lifes, portraits, and murals. Born in Montreal, she studied at the Art Association of Montreal under William Brymner and Maurice Cullen, later training with Randolph Hewton. A member of the Beaver Hall Group and a founding member of the Canadian Group of Painters, Robertson was influenced by both French modernism and the Group of Seven. She exhibited widely, including at the National Gallery of Canada, the Yale University Art Gallery, and internationally. Her later work featured bolder colors and expressive compositions, reflecting her deep appreciation for nature. Robertson's paintings are held in major collections, including the National Gallery of Canada, the Montreal Museum of Fine Arts, and the Art Gallery of Ontario.