John I, Duke of Brittany

John I (Breton: Yann, French: Jean; c. 1217/18 – 8 October 1286), known as John the Red due to the colour of his beard, was Duke of Brittany from 1221 to his death and 2nd Earl of Richmond in 1268.

John was the eldest of three children born to Duchess Alix and her husband and jure uxoris co-ruler, Duke Peter I. He became duke upon his mother's death in 1221. His father, who had reigned as duke due to his marriage to Alix, ruled as regent until John reached adulthood.

He experienced a number of conflicts with the Bishop of Nantes and the Breton clergy. In 1240, he issued an edict expelling Jews from the duchy and cancelling all debts to them. He joined Louis IX of France in the Eighth Crusade in 1270, and survived the plague that killed the king. The duchy of Brittany experienced a century of peace, beginning with John I and ending with Duke John III's reign in 1341.