Following the Mayan Rule storyline, Machine Man was badly damaged by the attacking Mayan gods and his original body was destroyed. He returned in a new body which he had apparently been working on several months before the attack.
X-51 was originally designed to be a killer as part of a US Army project to build robot soldiers. He had solar powered batteries built into his exoskeleton. All of the other robots in the series went insane after gaining sentience, while X-51, who has been called "the Robot with a soul", survived. He was raised as the human son of his creator, Dr. Abel Stack, who later died in an attempt to protect his "son" from a bomb intended for him.
The character was created by Jack Kirby and first appeared in Space Odyssey #8, although he was known as Mister Machine until Machine Man #1. The name change was due to licensing issues with a toy also named Mister Machine. Mid-way into his title, the writing and art chores fell to Tom De Falco and veteran artist (and Spider-Man co-creator) Steve Ditko and later Barry Windsor-Smith.
X-51 spent the most part of his first years pursued by the government; most notably Miles Brickman, who wished to use Machine Man to further his political career, and Colonel Kragg, who had lost his eye and several men to earlier models. Along the way, X-51 made friends with the likes of Peter Spaulding and Gears Garvin. Wanting to understanding humans more he took a job working at an insurance company where he developed a predictable unrequited love with his co-worker Pam Quinn.
In his early career, he also fought a number of super villains, such as Baron Brimstone and Jack o Lantern, and had several encounters with various superheroes like the Fantastic Four and the Hulk. He met Jocasta, the robotic "bride" of Ultron, after she was rejected from the Avengers and the two briefly fell in love before Ultron destroyed Jocasta. Not long after, Machine Man formed an alliance with the Avengers where he became a team reservist for the West Coast team.
His status with the Avengers was ultimately revoked after he was exposed to and infected by Sentinel technology, which caused him to lose self-control around mutants, eventually attacking two mutant superheroes. At the end of his second eponymous series, he encountered a monolith and was transported to the presence of the creators of the monolith, the Celestials.
Major Story Arcs
Machine Man is one of the five members of the Nextwave team. He prefers to be called Aaron. He pilots their ship, the Shockwave Rider, and is relied on by Monica Rambeau to perform various logistical functions as well as being an important fighter. He has a distaste for humans and other organic beings, which he refers to as "fleshy ones". He enjoys beer, and has wired his brain to be affected by it. He is slightly unpopular with his teammates because of his arrogance, and especially so with Elsa, who he seems to be attracted to, or he at least enjoys staring at her chest.
In the series it was revealed that the Celestials returned him to Earth after he had spent a year with them and they had determined that he was "complete and utter ☠☠☠☠". He's going to organize your sock drawer.
During the superhuman Civil War, Machine Man, and most of his Nextwave colleagues, sided with Captain America and his resistance. Once the "war" was over, however, he joined The Initiative citing that Maria Hill offered him a substantial amount of money to register. He was further compensated with a Life Model Decoy of Monica Rambeau; which he has programmed to cry.
He was placed on the Initiative team Operation Lightning Storm which was led by the Avenger Ms. Marvel and also had Sleepwalker, Spider-Girl and Wonder Man. During this time, he also pulled "a Wolverine" and simultaneously was an operative for ARMOR (Alternate Reality Monitoring and Operational Response). Here he was working alongside Morbius, Portal and Howard the Duck and on one mission to battle zombies he was reunited with his former love Jocasta.
When Norman Osborn rose to power during Dark Reign, Lightning Storm was disbanded which led to Machine Man and fellow Lightning Storm member Agent Sum briefly setting out to expose the villain Moonstone as the person impersonating the new Ms. Marvel. However nothing came of this and the plot point was abandoned and left unresolved.
Agent of SMASH
Steve Rogers and the Secret Avengers assigned Machine Man to keep the volatile new Hulk in check when he was acting on personal missions. The two unlikely allies became good friends over their time as partners and Machine Man helped the new Hulk battle an assortment of enemies such as the Sultan Magus, Black Fog, Ikaris of the Eternals and an invasion of Mayan Gods.
Red She-Hulk-Hell Hath No Fury
After success in dealing with the Red Hulk, Steve Rogers calls X-51 to help with the new Red She-Hulk situation. He had previously worked with Red She-Hulk, while with her father, and X-51 feels he has a good database on her already. He is able to track Betty to Arlington, Virginia, but by the time he has found her, she had already killed Vin Corsico, an inmate of the Raft. X-51 tries to revive Corsico but to no avail, he is then blind sided by Red She-Hulk. X-51 is able to fend off her attack but she gets away.
X-51 tracks Betty to Washington D.C., but when he makes contact she tries to fly away. X-51 then helps the Avengers try to stop her but Red She-Hulk gets away again. During the battle X-51 notices that Red-She-Hulk helps save civilians lives before fleeing. He tell Steve Rogers what he witnessed but Rogers is more intent on bringing Red She-Hulk to justice for the murder of Corsico.
After the Avenger fly off to chase Red She-Hulk, X-51 fallows her trail back to the house of Eleanor Bennett, where he meets Nikola Tesla and learns of the Terranometer. X-51 then tracks Betty to Deseched Island, in Puerto Rico. There X-51 helps her break in to the Echelon training facility. There the pair fight countless Echelon soldiers. X-51 comes to Betty's aide when she Hulks out and is captured by General Fortean.
After escaping the Echelon base, X-51 and Betty have a heart to heart where X-51 decides to help Betty on her mission to stop Echelon. The pair go back to Eleanor's house and find it destroyed. They are then attacked by the Military. X-51 is knocked out by a Echelon soldier who possesses an EMP bomb-like power. X-51 is later rescued by Red She-Hulk and the pair continue on their mission to stop Echelon.
Machine Man's powers include super-human strength, speed, durability and endurance. His body is made of titanium, and he has a cybernetic brain that gives him superhuman analytical ability. He has telescopic and detachable limbs which can be controlled when separated from the body.
Along with the built-in abilities for defense, X-51 has a multitude of devices, including anti-gravity generators that allow him to fly, built into his body. He also has sensors with zoom and magnifying capabilities, various radars, a chromatograph, seismometer, audiometer, transceiver and gravity wave detector. His fingertips contain lasers. He is virtually immortal as long as his programming/consciousness is kept secure. Any damage done to his body can simply be repaired.
Machine Man of Earth-398 was known as Sir MacHinery and was a member of the Queen's Vengeance.
Machine Man was a member of NEXTWAVE who was devoured by the zombified Power Pack.
Machine Man is rebuilt in the year 2020.
X-51 of the Earth X reality became the new Watcher.
X-51 appeared as a supporting character in the animated series Spider-Man Unlimited.
He first appearing in the fifth episode "Steel Cold Heart". X-51 was one of the High Evolutionary's servitors who was due to be scrapped. He was spared when Spider-Man interfered. Following this, he switched sides and he continued to appear in the series as one of John Jameson's Rebels following that appearance. He was voiced by actor Dale Wilson.