Joan (Stewart) Douglas Countess of Morton is Notable.
Joan (Stewart) Douglas Countess of Morton was born in Scotland.
Joan Stewart was born about 1428, the third daughter of James I , King of Scots and his queen-consort, Joan Beaufort. Joan was born both deaf and mute.
On 18 October 1440 (at the age of tweve) she was contracted to marry James Douglas, 3rd earl of Angus, but he died in 1446 before the marriage could take place. In 1445 she was sent to France, and after her sister Margaret's death she had been promised in marriage to her brother-in-law Louis, Dauphin of France later King Louis XI, but her inability to speak was noted as a reason the marriage didn't take place. She returned to Scotland in 1457.
She married before 15 May 1459 James Douglas, 1st Earl of Morton, son of James Douglas, 2nd Lord of Dalkeith and Elizabeth Gifford. They were granted a papal dispensation retroactively for their marriage on 7 January 1463/4 for being consanguineous in the second and third degrees.  There were four children from this marriage: 
Joan died on 22 June 1493, just four months before her husband. She is buried at Dalkeith Church, Midlothian, Scotland.
Date of Death
Douglas Richardson states that Joan was living 16 Oct 1486 but died before 1490. Alison Weir concurs that Joan died sometime after 16 October 1486 but notes only that she was buried in Dalkeith Church and does not hazard a guess as to the date of her death. It is not certain what source Cokayne's information is based upon.
↑ 1.01.11.21.31.4 Douglas Richardson. Royal Ancestry: A Study in Colonial and Medieval Families, 5 vols, ed. Kimball G. Everingham (Salt Lake City: the author, 2013), vol. 1, p. 659 BRUS 12.iii. Joan Stewart
↑ Burnett, George (ed). Rotuli Scaccarii Regum Scotorum (Exchequer Rolls of Scotland). Edinburgh: General Register House (1882), vol. 5 (1437-1454),vol. 5, preface pp. lxviii-lxix.
↑ 3.03.13.23.3 Weir, Alison. Britain's Royal Families. London: The Bodley Head (1989), p. 231.
↑ Paul, James Balfour. The Scots Peerage. Edinburgh: D. Douglas (1904), vol. 6, p.356.
Cokayne, George Edward. The Complete Peerage; or, A history of the House of lords and all its members from the earliest times. London: The St. Catherine Press, Ltd. (1936), vol. 9, p. 287.