Sir Alexander Stewart of Darnley (died 1404) was a Scottish nobleman, and a patrilineal ancestor of James VI and I.
He was the son of Sir Alexander Stewart of Darnley (d. after 26 August 1374) and Joanna. He married first Janet Turnbull of Minto and had at least one son with her. He married second Jonetta Keith, widow of David Hamilton of Cadzow, and daughter of Sir William Keith of Galston, and was granted his wife's lands of Galston by John Stewart, Earl of Carrick and they had six children:
With Janet:
With Jonetta