The Scottish surname Robertson is of patronymic origin, deriving from the personal name “Robert.” In Scotland  Robert was a popular personal name and the name of three kings of Scotland, including Robert the Bruce (1274–1329). The Robertson's are lineal descendants of the Celtic Earls of Atholl, whose progenitor was King Duncan I (Donnchadh in Scottish Gaelic), eldest son of Malcolm II. Today there are more than 150,000 people with the last name Robertson living in The United States.