M'Baku was one of Wakanda's greatest warriors, second only to his then friend T'Challa (Black Panther). M'Baku greatly disliked T'Challa's technological revitalization of Wakanda and sought to have all technology outlawed so the nation could return to its natural primitivism of several decades before. M'Baku had a contingent of supporters who shared this view. While T'Challa was on leave of absence from the throne in order to serve the Avengers in America, M'Baku plotted to usurp the throne. Wakandan culture had was traditionally ruled by it's greatest warrior. M'Baku therefore sought out to defeat T'Challa by reviving the outlawed White Gorilla cult, and to personally stalk and kill one of the rare white gorillas living in the jungles near Wakanda. Bathing in the gorilla's blood and eating the gorilla's flesh mystically endowed its great strength upon M'Baku.
When T'Challa returned with select members of the Avengers, M'Baku, calling himself the Man-Ape, openly challenged the Panther's right to rule. In the battle that ensued M'Baku succeeded in defeating the Panther. However, when he bound T'Challa to the giant statue of a panther which was the Panther cult's major totem and tried to topple it upon his enemy, the statue instead crumbled, burying him.
The believed dead Man-Ape was revived by his supporter N'Gamo and set out to track the Panther down and gain retribution. He tracked him to New York. There the Man-Ape allied himself with the Lethal Legion, kidnapped Monica Lynne, the Black Panther's American girlfriend, and sent word to T'Challa that he would have to once more engage him in mortal combat to free her. Through treachery, M'Baku once again bested the Panther, taking the Panther captive. When the Avengers came to the T'Challa's rescue, the Lethal Legion managed to ensnare them. Eventually, the Avengers broke free and defeated their captors, and Captain America physically bested the Man-Ape.
T'Challa decreed that the Man-Ape could never return to Wakanda without facing penalty of death. Humiliated, the Man-Ape never risked the attempt and instead wandered the less civilized parts of the world, performing mercenary work to survive. He was eventually contacted again by the Grim Reaper, who was trying to assemble a new Lethal Legion to exact revenge upon the Avengers. The Man-Ape was assigned to free Goliath from his incarceration on the West Coast Avengers Compound. Succeeding in the task, the Man-Ape allied with the Legion until the Reaper's racist attitudes prompted him to abandon the Legion's cause.