William Hay, 3rd Earl of Erroll PC (c. 1449 – 14 January 1507) was a Scottish peer.

William Hay was the son of William Hay, 1st Earl of Erroll and his wife, Beatrix, daughter of James Douglas, 7th Earl of Douglas.

He was the great-great grandson of King Robert II of Scotland and his first wife, Elizabeth Mure.

He was a member of the King James III's Privy Council and a commissioner for the 1482 peace treaty with England.

[2] He married first Lady Isabel Gordon, daughter of George Gordon, 2nd Earl of Huntly and Princess Annabella of Scotland, daughter of King James I of Scotland.