Mary Seton (1542 – 1615) was a Scottish courtier and later a nun. She was one of the four attendants of Mary Queen of Scots known as the Four Marys. She was a sister at the Convent of Saint Pierre les Dames in Rheims at the time of her death.
Mary Seton was the daughter of George Seton, 6th Lord Seton, and Marie Pieris, a French-born lady-in-waiting to Mary of Guise, the wife of King James V of Scotland. As a child, Mary Seton became a lady-in-waiting to the young Mary, Queen of Scots, along with three other girls of similar age and of a similar standing in Scots society. They were famously known as "The Four Marys": she and Mary Beaton, Mary Fleming and Mary Livingston. They were chosen by Marie de Guise, with the exception of Mary Fleming, for their Franco-Scottish parentage. The Four Marys accompanied Queen Mary in France, where she later married the Dauphin, Francis II of France. Mary Seton was the only one of the four not to marry, and continued in service with Mary, in Scotland and during her captivity in England.
When Queen Mary returned to Scotland, after her ceremonial entry at Edinburgh in September 1561, she went to Linlithgow Palace, while the four Marys, accompanied by the Queen's uncle, the Grand Prior of Malta, François de Lorraine, travelled west to Coldingham Priory and Dunbar. They stopped at the house of Mary Seton's brother George Seton, 7th Lord Seton, Seton Palace, for dinner. The Grand Prior then returned home through England making strategic plans of Berwick-upon-Tweed and Newcastle-on-Tyne. Mary Seton accompanied the captive queen back to Edinburgh after her defeat by the Confederate lords at the battle of Carberry Hill. Prior to the Queen's flight to England following the battle of Langside, Seton assisted her escape from the island fortress of Loch Leven by standing at a window dressed in the queen's clothes while Marie Stuart fled to the mainland in a small boat.