|Alternate Identity||Machine Man|
|Team Affiliations||Machine Men|
X-51 was found at a junk yard where Peter Parker and Shane Yamada-Jones were visiting. When he was about to be recycled he turned on and stated that he still had use. Then when a threat came and almost crushed shane it saved him. The Knights of Wundagore were not pleased and ordered to bring it back for studying. Seeing how it save Shane, Spider-Man decided to help the robot escape. He then had him stay in Naoko Yamada-Jones's clinic to rest. After a while a homing device triggered in him to come back to the Knights. Spider-Man then followed. After a battle and some arguments with the rebels, he was allowed to join the resistance and helped them from there on out. As the rebellion continued, X-51 was modified to appear as the modern version of the machine men.
X-51 is voiced by Dale Wilson.
In the Comics
X-51 uses the human name Aaron Stack and the superhero name Machine Man, and has been a member of the Avengers.