Tomás mac Ailein, sometimes known as Thomas of Galloway, was an illegitimate son of Alan of Galloway (c. 1175–1234), Constable of Scotland and the last Mac Fearghusa lord of Galloway. After the death of his father, who left no legitimate sons, King Alexander II of Scotland

Alexander II of Scotland

Alexander II was King of Scots from1214 to his death.-Early life:...

 planned to divide the lordship between the husbands of Alan's three daughters.

Thomas, along with his associate Gille Ruadh

Gille Ruadh

Gille Ruadh was the Galwegian leader who led the revolt against King Alexander II of Scotland. Also called Gilla Ruadh, Gilleroth, Gilrod, Gilroy, etc....

, led an unsuccessful rebellion against the king, with the aim of maintaining Galloway's status as an independent sub-kingdom. It is also possible that Thomas himself sired two sons of his own, that were known as Dougal and Fergus MacDouall of Wigtownshire.