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Real Name
Bartholomew "Barry" Aaron Stack (legally changed from Z2P45-9)
Current Alias

X-51, Barry Witherspoon, Aaron Stack


Dr. David Stack (father),
Aaron Stack ("brother") (formerly thought to be his previous form)




Red, (formerly gold due to artists' error)



Marital Status

Adventurer, formerly employee of an insurance agency

Robotic body seemingly filled with a human soul, now acts as a vessel of the heroic world.

Place of Birth


First appearance

Machine Man Vol 1 #1


Quote1 No, I don't care. I am not here to care. I am here to be a machine. Quote2
-- Barry Stack


After suffering the worst bipolar episode of his life and making threats on his life, David Stack realized that the best way to balance his son and his work would be to literally fuse them. He brought his son to his work after hours, and hooked him up to the Adamantium prototype Machine Man Z2P45-9. He attempted to transfer his son into the robot by electrocuting him and placing the currents from his son into the robot, powering it up with Aaron's thoughts inside. However, Stack's colleague Joe Kragg was also at the lab late, and noticed what the doctor was doing. He decided to blow the lab's electrical power in order to ensure the robot depowered. Instead, the lab was overloaded with electricity, killing both of the Stacks and awakening the robot, seemingly successfully containing the soul of Aaron Stack.

Undead, Orphaned Runaway Cyborg

Irrevocably shaped by his father's last words of wanting peace for the world, Aaron resolved to try to bring this wish to fruition. With no ties left, "Aaron" roamed the wilderness, helping others and, plagued by Aaron's fractured psyche, trying to destroy himself. He was repeatedly hounded, however, by the military and by Colonel Kragg. Being his first new interactions with humanity, the "robot side" of Aaron grew to mistrust his new peers. He only found solace when he was aided and offered a home by Doctor Leonard Samson, who had found the robot and didn't seek to turn him in. He acted as field support for him sometimes as Doctor Samson, the superhero, but mostly stayed in the background. Either way, he managed to dispatch Colonel Kragg, seemingly for good, while restoring Aaron's faith in humanity in the process.

During this time, Doctor Samson acted as a good friend and psychiatrist, trying to heal the robot's broken psyche and finding him employment at an insurance agency. He had to learn to manage his self-destructive tendencies, even though they tended to aid him in battle since he couldn't be destroyed. But when seeking a job, a former aide of Samson's known as the Binary Bug was seeking his revenge against the world, starting with this company. Aaron managed to stop him, but at the cost of his life. Aaron would go on to work at Delmar, and would secretly handle their cases involving superhumans as Machine Man.

Spreading His Business Around

Aaron first encountered other superheroes when he was tracking the recently-revealed supervillainess known as Ion due to the property damage she was causing. Terrified by her condition, she sought out the scientific aid of the Fantastic Four to help cure her. She caused a rampage in the Four's lab and was stopped by the Human Torch and Machine Man working in conjunction. He left afterwards on good terms, and the team said they owed him one for his help.

Machine Man next found himself fighting with the strangest of possible foes: the Hulk. At Doctor Samson's request, Barry tried to bring Banner in for psychological evaluation/therapy, outside the hands of the government. Banner said no, and a feud ensued. Machine Man proved the victor, gaining Hulk's respect. He would later battle the Hulk again alongside the Heroes for Hire before the four would unite to take down the crime lord known as Nightshade.

Before long, however, he found that his old foe Baron Brimstone had allied with the Sandman. It was up to he and Spidey to team up and stop them. TO BE CONTINUED...

Powers and Abilities


Current body

Power Grid [1]
Energy Projection
Fighting Skills


None known.

Strength level



  • Disassembling: Machine Man is capable of being disassembled in order to perform maintenance. If someone else figured out the exact way to disassemble Barry, they could do so without his consent.
    • Internal Attacks: Machine Man's wave-modifying coat was not extended to the inside of his body. As such, if disassembled, his internal parts are vulnerable to any form of energy attacks.
  • (Formerly) Mutants: After being infected with Sentinel technology, Barry would lose control and attack any mutants in his presence as the technology would override his free will. He lost this weakness upon adapting his current form.


Equipment: None known.
Weapons: None known.




  • Bartholomew Aaron Stack is the Earth-166 counterpart of X-51 (Earth-616) (better known as Machine Man).
    • This character's idea came about when trying to figure out a way to incorporate Draft227's alternate version of Amygdala into the strictly-Marvel SigmaVerse. Given the common first name, X-Factor had the idea to merge them. The resulting idea involved a mentally ill patient who was experimented on by the Leader, and later placed into a robot body. The Hulk aspect was removed to create the full Machine Man seen here, and the Hulk aspects were solely retained for SigmaVerse's Aaron Stack.
    • In canon, Z2P45-9 took the name "Bartholomew" because Barry sounded like Aaron. In our world, it's to match the Barry Witherspoon aspect of his counterpart.
      • Whenever Aaron is forced to use a different name to go undercover, he uses the name "Barry Witherspoon." This is a further allusion to the Earth-616 character.
  1. OHOTMR #1


  • In researching the character, Machine Man became one of Uncanny X-Factor's new favorite characters.
  • Barry's role in the Heroes for Hire replaces that of Dane Whitman in Earth-616's continuity.
  • As soon as he hit the public radar, Barry was inducted into SHIELD's superhuman index. It has been hinted on more than one occasion that SHIELD is responsible for the Machine Man project, meaning they would have known of him even before he was created.
  • Due to his encounters with The One Above All, Barry Stack believes in God.
  • Barry Stack is intended to be a full reboot of the Machine Man, while the Ultimate version stays closer to the classic version.
  • Uncanny X-Factor has condemned the song written for the character by the band Powerman 5000.
    • Uncanny X-Factor claims to have written his own song in response. It was never released. He has also claimed it's simply a reworded Mr. Roboto by Styx, but neither piece has ever been seen by human eyes.
    • X-Factor also tried to remove all "metallic" references to/origins of the character, but included the mental illness intentionally to make him more realistic.
  • Barry has openly admitted that if he were a human, he would be an alcoholic.
  • When Barry realized he no longer contained the essence of Aaron Stack, he went into isolation in the desert for a week and did nothing but drink and cry. When he returned, he only allowed people to call him Bartholomew. He told no one of this.

See Also

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