Alexander Stewart (1477 – 19 December 1537) was a Scottish prelate; also known as Alexander Stewart of Pitcairn. He was the son of Alexander Stewart, Duke of Albany, and his first wife Catherine Sinclair, daughter of William Sinclair, Earl of Orkney and Earl of Caithness. The marriage of his parents was dissolved in 1478 and his father remarried, but it was not until 1516 that an act of parliament made the marriage unlawful and ensured that Alexander Jr. would be regarded as legally illegitimate and unable to inherit his father's title.