Muckman was originally a garbageman named Garson Grunge who was mutated into a walking pile of garbage when Bebop and Rocksteady poured mutagen out a window that then landed on him. The accident also mutated his friend, Joe Junkee. They took the names Muckman and Joe Eyeball. The two were initially enemies of the Turtles, because they held them responsible for their mutation.
April and Irma scoured the city in search of the two missing garbage men. When they fond their garbage truck, April contacted the Turtles, only to find themselves face-to-face with Muckman and Joe Eyeball. The Turtles track April and Irma to the alley behind Tropotron Labs but as soon as they get close to the two new mutants in town, they suddenly become very weak. In their weakened state, the Turtles are unable to save April and Irma and they are carried off by Muckman.
Elsewhere, Shredder, Rocksteady and Bebop had returned to the Earth's surface to locate Muckman. They find him and convince Muckman that the Turtles mutated Bebop and Rocksteady. The two groups than form an alliance.
However, the Turtles track April's Turtlecom to discover that Muckman and Joe Eyeball have teamed up with Shredder. As soon as Muckman and Joe Eyeball get close, the Turtles collapse. Splinter arrives and is taken prisoner by Bebop, Rocksteady, and Shredder who prepare to return to the Technodrome. Shredder leaves the unconscious Turtles to Muckman.
However, Muckman and Joe Eyeball became allies of the Turtles after discovering that Bebop and Rocksteady caused their mutation and help them rescue Splinter from Shredder. After Shredder and Co. had been defeated, Donatello told Muckman that he might be able to find a way to make him and Joe Eyeball normal again, but Muckman told him to take his time as they were now mutant heroes.
- Muckman was given a voice similar to that of Jackie Gleason's character Ralph Kramden from the classic television series The Honeymooners.
- He made a slight appearance in the 2012 TV series episode "Invasion of the Squirrelanoids" on a poster inside Mikey's wall in his room, before his counterpart debut.