Grand Ma[i]gne or Vieux Ma[i]gne was a Frankish castle in the Mani Peninsula, Greece. It was built, according to the Chronicle of the Morea, ca. 1248–1250 CE by William II Villehardouin, the Prince of Achaea in order to control the Slavic tribe of the Melingoi which occupied Mount Taygetos. Villehardouin was captured by the Byzantines in 1259 at the Battle of Pelagonia and was forced to surrender the castle as ransom for his release.