Robert III de Brus

Robert III de Brus (fl. 12th century, died ca. 1191) was the oldest son of Robert de Brus, 2nd Lord of Annandale.

He predeceased his father, and so did not inherit the lordship of Annandale, which passed to his brother, William de Brus, 3rd Lord of Annandale. He married in 1183 Isabella Mac William (Isibéal inghean Uilleim), illegitimate daughter of King William I of Scotland through the latter's liaison with a daughter of Robert Avenel lord of Eskdale. There were no children.

His great-great-great-nephew was his famous historical namesake, King Robert I of Scotland.