Grace Marks (c. 1828 – after c. 1873) was an Irish-Canadian maid who was involved in the 1843 murder of her employer Thomas Kinnear and his housekeeper, Nancy Montgomery, in Richmond Hill, Ontario.

[1] Marks was employed as a maid in the house of Yonge Street farmer Thomas Kinnear, who was in a sexual relationship with his housekeeper, Nancy Montgomery.

[2][3] Kinnear was shot and Montgomery, who was pregnant at the time of her death, was hit on the head with an axe and subsequently strangled before being dismembered and hidden under a large tub.

Before McDermott was hanged, he insisted that Marks was, "an evil genius who masterminded the double murder, then feigned mental illness in order to avoid the gallows".

She is the subject of Margaret Atwood's historical fiction novel Alias Grace and played by Sarah Gadon in the 2017 television adaptation directed by Mary Harron.