Genseric (from Gaiserich, prince of the spear), a Vandal conqueror, bastard brother and successor of Gonderic, died in 477. The Vandals had passed the Alps and the Pyrenees, and devastated and conquered a large part of Spain. In 429, when the weak and debauched Valentinian III. occupied the throne of the crumbling western empire, they were called to the province of Africa by Boniface, the governor, who had been induced by intrigues and the fear of a rival to betray his master. Eager for conquest, these northern barbarians prepared a fleet, and were ready to embark when the unexpected attack of Hermanric, king of the Suevi, and the ravages of this people on the possessions of the Vandals, delayed their departure. Having routed the Suevi in a bloody battle near Augusta Emerita (Merida), Genseric embarked with about 50,000 men, crossed the straits of Gibraltar, and conquered within two years all the cities in Mauritania. When Boniface, repenting of his crime, desired Genseric to return to Spain, he refused and could not be expelled; but he at last agreed in a treaty (435) to be satisfied with Mauritania and Nu-midia. But the native inhabitants of the Atlas mountains, so long oppressed by the Roman governors, and the Donatists, driven to despair by the persecutions of the orthodox church, joined the standard of Genseric, who soon took up arms again and subdued the whole province of Africa. In 439 he took Carthage and made it the capital of the Vandal empire, which now extended over the whole coast, and by piratical expeditions was established in parts of Italy, Sardinia, and Corsica. The attacks of the Huns in the north of the Roman empire made these aggressions on its southern provinces easier, and it was Genseric who invited Attila to his fatal march to Gaul (451). Rome escaped the hands of the Huns, but fell into those of the Vandals. Invited, as is said, by Eudoxia, widow of Valentinian III., who wanted to avenge the murder of her husband by Maximus, Genseric crossed the Mediterranean, sailed up the Tiber, took Rome, pillaged it for 14 days (June, 455), carried away Eudoxia and her daughters, one of whom he gave to his son Hunneric, and sent the Roman treasures and captives to Carthage. All the shores of the Mediterranean, from Asia Minor and Egypt to the straits of Gibraltar, were now ravaged by the Vandals. A fleet, sent by the emperor Majorian (457) to check these ravages, was destroyed in the bay of Cartagena; nor was another sent by the Byzantine emperor Leo (408) more successful; and Genseric reigned victoriously until his death.

He was of middle stature, lame of one leg in consequence of a fall from a horse, slow and cautious in his speech, cunning, treacherous, cruel, an able general, and a skilful ruler. Professing the Arian creed, he compelled those who adhered to the orthodox faith to leave his domains, and when they remained treated them as slaves. He was succeeded by Hunneric.