Robert Fitzwalter was a prominent English nobleman in the 12th and 13th centuries. He was born around 1160 and became known for his role as a baron and military leader. Fitzwalter was a key figure during the reign of King John of England, particularly during the conflicts that arose from the king's unpopular rule. Fitzwalter is best remembered for his involvement in the Magna Carta movement. In 1215, he was one of the barons who opposed King John, leading to the creation of this historic document that limited the powers of the monarchy and established certain legal rights for subjects. His actions contributed significantly to the development of constitutional law in England.