Gaiseric (gĪˈsərĭk) [key] or Genseric gĕnˈsərĭk, jĕnˈ–, c.390–477, king of the Vandals and Alani (428–77), one of the ablest of the barbarian invaders of the Roman Empire. He led (429) his people from Spain into Africa, possibly at the request of Boniface, and quickly subdued a large territory, which was later (435) ceded to him by treaty. He took Carthage in 439, sent a fleet to raid Sicily in 440, and gained recognition of his independence in 442. He then dispossessed many Roman landowners and persecuted the Roman Catholic clergy, meanwhile gaining control of the Mediterranean through his pirate fleets. In 455 he sacked Rome. In 460 he caused the failure of an expedition sent against him by Majorian, and in 468 he undermined a similar attempt by Leo I. By the time of his peace (476) with Zeno, his lands included Roman Africa, Sicily, Sardinia, Corsica, and the Balearic Islands.