Man Mountain Marko was a member of the Maggia and a loyal lieutenant to Silvermane. He was sent by Silvermane to steal the ancient tablet taken by the Shocker. He was confronted and defeated by Spider-Man.
He then threatened Curt Connors until the scientist agreed to work with Louis Wilson to crack the Lifeline Tablet's secret code.
When Silvermane drank the elixir of life, made with the tablet's formula, at first he was deceived by Caesar Cicero into thinking that the young man was an impostor; nevertheless, when Spider-Man busted in the Galby Building, he tried to protect his master, but he was easily defeated again.