Earl of Erroll is a title in the Peerage of Scotland. It was created in 1453 for Sir William Hay. The subsidiary titles held by the Earl of Erroll are Lord Hay and Lord Slains (1452), both in the Peerage of Scotland. The Earls of Erroll also hold the hereditary office of Lord High Constable of Scotland. The office was once associated with great power. The Earls of Erroll hold the hereditary title of Chief of Clan Hay.

The Lord High Constable is a hereditary, now ceremonial, office of Scotland. In the order of precedence of Scotland, the office traditionally ranks above all titles except those of the royal family. The Lord High Constable was, after the King of Scots, the supreme officer of the Scottish army. He also performed judicial functions as the chief judge of the High Court of Constabulary. From the late 13th Century the Court – presided over by the Lord High Constable or his deputies – was empowered to judge all cases of rioting, disorder, bloodshed and murder if such crimes occurred within four miles of the King, the King's Council, or the Parliament of Scotland. Following James VI's move to England, the jurisdiction of the Lord High Constable was defined in terms of the "resident place" appointed for the Council.