- See also Margaret Stewart.
Margaret Stewart, Countess of Angus and Mar (died 1417) was Countess of Angus and Lady of Abernethy in her own right. Her father was Thomas Stewart, 2nd Earl of Angus.
She was the widow of Thomas, Earl of Mar. By an illicit affair with William Douglas, 1st Earl of Douglas, husband of the Earl of Mar's sister, she became the mother of George Douglas, 1st Earl of Angus (c. 1380-1403), and secured a charter of her estates for her son, to whom in 1389 the title was granted by King Robert II.