Jerome Beechman was born a mutant in the small town of Los Alamos in New Mexico. Rejected by everyone around him due to his hairy and freakish appearance his father abandoned him in a desert when he was ten years old. He swore revenge on those who mocked him and began to wander the desert. While wandering the desert he ran into Nekra, a runaway albino mutant who was also lived in Los Alamos. The two of them grew close over the years as they wandered from place to place. One day while in New Mexico a group of teenagers attacked the duo because of their freakish appearances. The duo became cornered and their mutant powers manifested, killing several of the teenagers.
Years later taking the name Mandrill he launched a political scheme in order to take over several small African nations alongside Nekra. However Shanna The She-Devil became involved and defeated the two mutants and they were taken into S.H.I.E.L.D. custody. Somehow the two mutants escaped S.H.I.E.L.D. and founded the organization called Black Spectre. The group was then opposed by Shanna, Daredevil, Black Widow, and the Thing. During the fight Nekra was captured, but Mandrill managed to escape.
After his last plot failed he approached his world conquest scheme from a different angle and hypnotized a group of women and forced them to do his bidding as Fem-Force. He also recruited the mutant super villain team called Mutant Force in order to help him in his plot. The Defenders eventually learned of the plot and managed to capture Mutant Force. Mandrill then retreated after being beaten by the Defenders several times. Mandrill then proceeded to become an arms dealer by selling Wakandan technology, but was stopped by Black Panther. Mandrill then decided to have his revenge against his family and attacked the nuclear power plant where his parents worked. Once again, the Defenders defeated him, and he was shot by his mother Margaret, who was immune to his pheremones.
Mandrill eventually recovered and learned that Grim Reaper killed Nekra. Enraged and crazed he attacked the Grim Reaper, who during the battle managed to seemingly kill him. Yet sometime later Mandrill showed up at an auction that was stopped by Spider-Man and Alpha Flight. Mandrill was then incarcerated in the Vault, where he was a member of Crossfire's mind control gang; though he managed to escape, he was stopped a few yards from the prison by the Thunderbolts. He was later moved to the minaturized prison known as the "Big House" where he played a key role in the mass break out that was foiled by the She-Hulk. He was then transferred to the Raft and managed to escape when Electro started a mass breakout. Rejoining the other members of Crossfire's gang, he participated in Crossfire's running battle against the U-Foes before he and the others were captured by the Avengers.
His current whereabouts are unknown. It is unsure if he was one of the many mutants who were depowered during the House of M event.