William Hay, 4th Earl of Erroll

The Right Honourable The Earl of Erroll
Arms of the Earl of Erroll
8th Lord High Constable of Scotland
In office 1507–1513
Preceded by	William Hay
Succeeded by	William Hay
Personal details
Born	1470 Huntly, Aberdeenshire, Scotland
Died	9 September 1513 (age 42 or 43) Battle of Flodden, Northumberland, England
Spouse(s)	Christian Lyon Margaret Kinloch

William Hay, 4th Earl of Erroll (1470 – 9 September 1513), styled as Lord Hay until 1507, was a Scottish peer and soldier. He was killed at the Battle of Flodden.

William Hay was the son of William Hay, 3rd Earl of Erroll. He had double royal lineage: his grandfather, William Hay, 1st Earl of Erroll was a great-great grandson of King Robert II of Scotland; and his maternal grandfather was James I of Scotland.

He served as the Lord High Constable of Scotland, a hereditary title that was, after the king, the supreme officer of the Scottish army. He was killed on 9 September 1513 in the Battle of Flodden, near Branxton, Northumberland. He died alongside his younger brother Thomas, King James IV of Scotland and more than a dozen dukes and earls in a decisive English victory.

He married Christian Lyon, daughter of John Lyon, 3rd Lord Glamis, and had two children:

He married secondly Margaret Kinloch of Cruvie, widow of Sir James Sandilands, 5th feudal baron of Calder.