Alexander Hay, Lord Fosterseat (c.1560–1640) was a 16th/17th century Scottish judge and Senator of the College of Justice.
He was the son of Alexander Hay (d.1594) Clerk Register of the High Courts in Edinburgh.
[1] His country estate was at Fosterseat House, in northern Scotland (historically this name appears both near Elgin and near Forfar).
In February 1604 he was elected a Senator of the College of Justice under the title of Lord Fosterseat, elected alongside Sir Lewis Craig of Wrights Land.
His brother-in-law through marriage as Sir Robert Richardson of Pencaitland.