Robert Marmion (died 1144) was an Anglo-Norman baron and soldier who rose to prominence during the wars between King Stephen and the Empress Matilda.
He also entered into contention with William Beauchamp over tenure of Tamworth Castle, where before 1135 he received a grant of free warren from King Henry I of England.
[4] When civil war broke out in 1139, he rallied to the side of King Stephen and was sent to hold Falaise Castle in Normandy against attack from Matilda's husband, Geoffrey of Anjou.
He proved to be "a warlike man with no match for boldness, fierceness or cunning" and his successful defence led Geoffrey to destroy his ancestral castle of Fontenay in reprisal.
He expelled the monks from the nearby St Mary's Priory and made its stone buildings into a fortified base for launching attacks on the castle.