Ralph de Monthermer, 1st Baron Monthermer

Ralph de Monthermer, 1st Baron Monthermer (c. 1270 – 5 April 1325), between 1297 and 1307 jure uxoris Earl of Gloucester and Earl of Hertford, and between 1306 and 1307 also 1st Earl of Atholl, was an English nobleman, who was the son-in-law of King Edward I. His clandestine marriage to the King's widowed daughter Joan greatly offended her father, but he was quickly persuaded to pardon Ralph.