William Stewart of Monkton and Carstairs (died 1588) was a Scottish landowner and courtier.
Richard Musgave of Carlisle complained about goods sold at Kirkcudbright in 1581, involving Stewart.
[3] In November 1584 James VI granted him a pension from the lands of Whithorn Priory which had previously been paid to his sister-in-law, Margaret Stewart, Mistress of Ochiltree.
[9] The murder followed a quarrel in the king's presence in which, according to David Calderwood, Stewart asked to Bothwell to kiss him behind.
This William Stewart killed James Douglas, Lord Torthorwald, a son of George Douglas of Parkhead, in Edinburgh on 14 July 1608, in revenge for the murder of his uncle James Stewart, Earl of Arran.