Robert III, born John Stewart, was King of Scots from 1390 to his death in 1406. He was also High Steward of Scotland from 1371 to 1390 and held the titles of Earl of Atholl (1367–1390) and Earl of Carrick (1368–1390) before ascending the throne at about the age of 53 years. He was the eldest son of King Robert II and Elizabeth Mure and was legitimized by the second marriage of his parents and by papal dispensation in 1349.

The Mormaer or Earl of Atholl was the title of the holder of a medieval comital lordship straddling the highland province of Atholl, now in northern Perthshire. Atholl is a special Mormaerdom, because a King of Atholl is reported from the Pictish period. The only other two Pictish kingdoms to be known from contemporary sources are Fortriu and Circinn. Indeed, the early 13th century document known to modern scholars as the de Situ Albanie repeats the claim that Atholl was an ancient Pictish kingdom. In the 11th century, the famous Crínán of Dunkeld may have performed the role of Mormaer.