Genseric (c. 389 – January 25, 477), also spelled as Geiseric or Gaiseric, is King of the Vandals and Alans (428–477) and is one of the key players in the troubles of the Western Roman Empire in the 5th century.

During his nearly 50 years of rule, he raises a relatively insignificant Germanic tribe to the status of a major Mediterranean power — which, after he dies, enters a swift decline and eventual collapse.

Succeeding his brother Gunderic at a time when the Vandals are settled in Baetica (modern Andalusia, Spain), Gaiseric transports all his people, around 80,000, to Northern Africa in 428.

He might have been invited by the Roman governor Bonifacius, who wishes to use the military strength of the Vandals in his struggle against the imperial government.

Gaiseric causes great devastation as he moves eastward from the Strait of Gibraltar across Africa.

He turns on Bonifacius, defeats his army in 430, and then crushes the joint forces of the Eastern and Western empires that have been sent against him.

In 435, Gaiseric concludes a treaty with the Romans under which the Vandals retain Mauretania and part of Numidia as federates (allies under special treaty) of Rome.

In a surprise move on October 19, 439, Gaiseric captures Carthage, striking a devastating blow at imperial power.

In a 442 treaty with Rome, the Vandals are recognized as the independent rulers of Byzacena, and part of Numidia.

Gaiseric’s fleet soon comes to control much of the western Mediterranean, and he annexes the Balearic Islands, Sardinia, Corsica, Malta and Sicily.

His most famous exploit, however, is the capture and plundering of Rome in June 455.

Subsequently the King defeats two major efforts of the Romans to overthrow him, that of the emperor Majorian in 460, and that led by Basiliscus at the Battle of Cape Bon in 468.

After dying in Carthage at the great age of 88, Gaiseric is succeeded by his son Huneric.