Attuma was born into the tribe of Homo mermanus who eschewed civilization to live as nomadic barbarians. For some unrecorded reason, Attuma was endowed with strength far surpassing that of his people. Nearing adulthood, Attuma learned of a prophesy, in the lost Atlantean Chronicles, of a conqueror who would take the empire of Atlantis by force. Believing he is that conqueror, Attuma has launched numerous attacks on the city of Atlantis and its regent Namor the Sub-Mariner.
Unable to best Namor in personal combat, Attuma has frequently taken allies to further his ambitions. These alliances have also met with defeat. The first time Attuma attacked Atlantis, the Fantastic Four aided Namor in repulsing his attack. In recent years, Attuma has battled the Avengers as well. Not renowned for his intelligence, Attuma has frequently employed renegade Atlanteans (Deep Six) and human scientists. One of them created the Octo-Meks, octopus-shaped fighting machines. Another proposed that he mate with human mutants in order to produce a sire stronger than Namor himself. Toward this end he abducted the mutant Phoenix, but she thwarted his plans. Although Attuma has never been able to claim a lasting victory over Namor, he was a party to the death of Namor's bride, Lady Dorma. Attuma is still at large in the Atlantic Ocean, having never been imprisoned for any of his deeds.
After Namor was asked to abdicate the throne of Atlantis, a ruling council was appointed consisting of Lord Dara, High Priest Shakkoth, Warlord Thakos, and Grand Vizier Vashti. Shakkoth started an Atlantean civil war so that he could obtain the throne, and the other three formed an alliance with Attuma and his barbarian hordes in order to survive the civil war. Attuma, seeing this as an opportunity to rule Atlantis, consented. Once the civil war was crushed, leaving the Atlantean military greatly weakened. Attuma easily assumed rule of the city. When certain citizens began longing for Namor’s return, Attuma put together a plot that would cause the Atlantean citizens to lose faith in Namor.