John of Brittany or Jean de Bretagne (c. 1266 – 17 January 1334) 3rd Earl of Richmond, was an English nobleman of Breton origin. He entered royal service under Edward I, and fought in the Scottish Wars. John of Brittany was not an accomplished soldier, and among the earls of England he was politically quite insignificant. He was nevertheless a capable diplomat, valued by both Edward I and Edward II for his negotiating skills. He was appointed Guardian of Scotland by Edward I in 1305, and confirmed in this position by Edward II. Although he was generally loyal to Edward II during the times of baronial opposition, he eventually supported the coup of Isabella and Mortimer. He then retired to his estates in France, and for the rest of his life remained politically inactive.
His mother Beatrice was the daughter of Henry III of England, which made John the nephew of Henry's son and heir Edward I. John of Brittany, Earl of Richmond in Wikipedia