Gaiseric (389 – 25 January 477), also known as Geiseric or Genseric (Gaisericus, Geisericus; reconstructed Vandalic: *Gaisarīx) was king of the Vandals and Alans from 428 to 477. He ruled over a kingdom he established and played a key role in the decline of the Western Roman Empire during the 5th century. Through his nearly fifty years of rule, Gaiseric raised a relatively insignificant Germanic tribe to the status of a major Mediterranean power.
The illegitimate son of King Godigisel, Gaiseric became king of the Vandals upon the death of his half-brother, Gunderic. In 428/429, under Gaiseric, the Vandals crossed from the Roman province of Hispania Baetica into North Africa, and by 439 he had established a powerful Vandal kingdom with Carthage as its capital. The wealth of his new lands allowed the Vandals to construct a large fleet and subsequently seize the Balearic Islands, Sardinia, Corsica and Malta, exerting effective control over much of the western Mediterranean.
The murder of Roman Emperor Valentinian III, who had betrothed his daughter to Gaiseric's son Huneric, led the Vandal king to invade Italy. The invasion culminated in his most famous exploit, the capture and plundering of Rome in June 455. Gaiseric repulsed two major attempts by both halves of the Roman Empire to reclaim North Africa, inflicting devastating defeats on the forces of Majorian in 460 and Basiliscus in 468. As a result, the Romans abandoned their campaign against the Vandals and concluded peace with Gaiseric. Gaiseric died in Carthage in 477 and was succeeded by Huneric.
Gaiseric was an illegitimate son of King Godigisel and a slave woman. After his father's death in a battle against the Franks during the Crossing of the Rhine, Gaiseric became the second most powerful man among the Vandals, after the new king, his half-brother Gunderic—long before his more formal accession to the kingship. Jordanes described Gaiseric in the following manner:
Gaiseric...was a man of moderate height and lame in consequence of a fall from his horse.