Gelimer (original form possibly Geilamir, 480–553), King of the Vandals and Alans (530–534), was the last Germanic ruler of the North African Kingdom of the Vandals. He became ruler in June 530 after deposing his first cousin, two generations removed, Hilderic, who had angered the Vandal nobility by converting to Catholic Christianity, as most of the Vandals at this time were fiercely devoted to Arian Christianity.
The Eastern Roman Emperor Justinian I, who had supported Hilderic, soon declared war on the Vandals, ostensibly to restore Hilderic. In June 533, Justinian sent an expeditionary force commanded by Belisarius which finally reached Africa in the beginning of September. Meanwhile, in Sardinia, which formed part of the Vandal domain, the governor Godas, a Visigoth, revolted against Gelimer and began to treat with Justinian as an independent sovereign. Gelimer, ignorant or contemptuous of Justinian's plans, sent a large army consisting of most of the available army in Africa under his brother Tzazo to crush the rebellion, meaning that the landing of Belisarius was entirely unopposed.
On landing, Belisarius immediately marched for Carthage, finally meeting resistance on 13 September when he was confronted by Gelimer at Ad Decimum, 10 miles from Carthage. Although outnumbered 11,000 to 17,000 the battle was evenly fought by the Vandals until Gelimer's brother Ammatas was killed, at which time Gelimer lost heart and fled. On 14 September 533, Belisarius entered Carthage and ate the feast prepared for Gelimer in his palace. However, Belisarius was too late to save the life of Hilderic, who had been slain at Gelimer's orders as soon as the news of the landing of the imperial army came.