Sir Alexander Seton of Pitmedden, 1st Baronet, Lord Pitmedden (c. 1639 – 29 May 1719) was a Scottish advocate, a Senator of the College of Justice, a Lord of Justiciary, and a Commissioner.
Seton was a son of John Seton of Pitmedden who commanded a detachment of Royalist troops at the battle of the Bridge of Dee and, while riding along the riverside with Lord Aboyne was shot through the heart by a cannonball, age 29. John Seton's two sons were both infants at the time. With their mother, Elizabeth, daughter of Sir Samuel Johnston, 1st Baronet of Elphinston, they were driven from their house which was plundered, and the whole rents of their estate seized by the Covenanters. Their mother remarried, the Earl of Harfell, and the boys were taken in by their kinsman, George Seton, 4th Earl of Winton, who later enrolled them both at the University of Aberdeen. James Seton of Pitmedden, the elder brother, became an officer in the English Navy. During the Dutch attack on the English fleet at Chatham in 1667, he was severely wounded and died soon afterwards. He was succeeded by his brother, Alexander.
He became a member of the Faculty of Advocates on 10 December 1661, and was knighted by King Charles II in 1664. He was appointed an Ordinary Lord of Session on 31 October 1677, when he assumed the title of Lord Pitmedden. He was later appointed a Lord of Justiciary, on 5 July 1682.
On 15 January 1684, he was created a baronet of Nova Scotia by King Charles II.
He represented Aberdeenshire in the Scottish Parliament in 1681, 1685, and 1686, and for his boldness and independence in opposing the repeal of the Test and Penal Laws proposed by King James VII, he was deprived by that monarch of his seat on The Bench. He was at the same time removed from the Court of Justiciary.