Man-Mountain Marko was created by Stan Lee and John Buscema in 1969 and first appeared in The Amazing Spider-Man # 73.
A petty criminal who gained low level super-human strength through steroid abuse, he was an early enemy of Spider-Man, Power Man (Luke Cage), and Iron Fist. Later it would be discovered by Spider-Man that the steroid abuse had caused severe damage to his liver, and that he would eventually die because of it.
Man Mountain devoted the remainder of his life to making a positive difference in his community but eventually a cure for his condition was found. Marko did not encounter Spider-Man again for several years, and it was in this encounter it was revealed that Marko's strength was a result of regular doses of steroids.
Marko appeared next when pieces of a lost lifeline tablet were discovered and Cicero sought out the pieces. Marko and Cicero were defeated, and despite his failure, Cicero kept Marko as his flunky.
Marko develops a singing career, focusing on the concept of violence against female super-heroes. While on a plane with the super-hero Dazzler he becomes enraged over the perceived lack of alcohol. He injures passengers and takes a hostage, he breaks the hostage's wrist to prove he is serious. Dazzler, at low power, manages to subdue him.
He was eventually hired by Norman Osborn to run a section of H.A.M.M.E.R. as part of a fact finding mission to an 'Atlas' facility run by a younger Jimmy Woo. Atlas is an international crime organization that is working against the government's interests. Marko is working as the head of a squad of B.A.T.F.E. government agents. Marko's forces including a seeming snitch that had been advising the government on the activities of Atlas. Marko, against the recommendation Bureau of Alcohol, Tobacco, Firearms and Explosives of his guides, rushes off the recommended path to follow the snitch. The man is really Jimmy Woo. Before Marko can do anything about the situation, he is eaten by a sentient dragon named Lao. This was against Woo's wishes. Marko is replaced by another super-powered strongman, the Grizzly.