- —Justin Hammer[src]
Justin Hammer was an unscrupulous British industrialist and head of various international design and manufacturing firms. A long time competitor of Stark International, he was born in Surrey, England, where he began his company Hammer Industries, which became one of the leading weapons suppliers in the world after Stark International moved out of weapons production. Hammer maintained other manufacturing interests besides weapons, and it was while bidding for an plant, to be built within the borders of the small Communist country of Carnelia, that Stark and Hammer came into direct conflict.
Knowing that Iron Man was an essential part of Stark International's image as well as its security (but not knowing that Iron Man was actually Anthony Stark), Hammer directed his engineers to develop a means to override Iron Man's armor. The engineers eventually built a hypersonic device able to breach the armor's refractory coating. Over a period of weeks they tested their ability to override the cybernetic circuitry of the armor by activating various weapons systems against Iron Man's will. Iron Man dismissed these incidents as mechanical malfunction rather than a deliberate override. Finally Hammer activated Iron Man's repulsor unit, causing Iron Man to publicly kill Sergei Kotzinin, the Carnelian ambassador to the United Nations. His armor impounded, Tony Stark tracked the reclusive Hammer to the Mediterranean Sea, where he was taken captive by Hammer's mercenaries. There he learned about Hammer's designs upon him, as well as some of his shadier operations, such as the financing and outfitting of various costumed criminals in exchange for fifty percent of their profits. Stark managed to wreck the device that could override his armor and then donned his spare suit in time to battle Hammer's reserves, a small army of powerful costumed criminals. Vanquishing them, Iron Man damaged Hammer's floating villa and captured the man who designed the equipment that overrode his armor. Justin Hammer managed to escape. Although Iron Man was able to clear himself of the murder charge by exposing certain of Hammer's activities, he could not effectively implicate Hammer or thwart Hammer's operations, since his diverse corporate holdings are unknown to the authorities.
Iron Man encountered Hammer a second time when he kidnapped Stark's girlfriend Bethany Cabe and brought her aboard his huge submarine. Iron Man managed to severely damage the vessel but was unable to apprehend Hammer.
When Stark's nemesis entrepreneur Obadiah Stane committed suicide, Hammer managed to get all the stocks of Stane International, even though Stark believed he had transformed Stane International back into Stark International.
Justin Hammer was a reclusive billionaire overseeing various international business interests, legal and otherwise. Among the many costumed criminals whom he has outfitted and financed operations for are Blacklash (aka Whiplash), Blizzard, Melter, Man-Killer, Beetle, Spymaster, Leapfrog, Porcupine, Water Wizard, Scorpion, Stiletto, Discus, the Constrictor, Blue Streak, and Captain Barracuda. Among those one of Hammer's companies has built weaponry for are the Orb, Viper, the Black Spectre and Zodiac criminal organizations.
Hammer also collaborated with the Hand, Hydra and other criminal organizations in plots against Stark and Iron Man. When one of those plots failed, Hammer was forced to relinquish his schemes against Stark's interests and to sell Stark all the stocks of Stane International for a nominal price.
Some time later, Hammer discovered that he had cancer and would soon die; he relocated to a space station in Earth’s orbit, believing that null-gravity would prolong his life. Determined to bring down his greatest rival, he again employed Philip Barnett and hired the Spymaster (Nathan Lemon) and Espionage Elite to assault Stark and plant “rogue cells” designed by Barnett within Tony’s body. Over time, these cells activated and began to adversely affect Stark, causing him to first become more aggressive and competitive, then increasingly pragmatic and violent. Tony was released from the cells by his friends Jocasta and James Rhodes, and Iron Man confronted Hammer aboard his space station. Hammer managed to incapacitate Iron Man within an energy field suspended over a pool of water, but when he saw that Barnett was attempting to flee the station in an escape pod, he activated the pod’s self-destruct device. Unfortunately for Hammer, the pod was too close to the station and the explosion knocked him into the pool. Iron Man set himself free from the field and blasted a hole through the station’s hull; Hammer was blown into space with the water and instantly froze; observing Hammer’s frozen body drifting in space, Iron Man reflected that his old foe would now “live forever.” 
- Justin Hammer uses a cigarette holder when smoking his cigarettes. This used to be a fashionable way of smoking for much of the 20th century.
- For reasons of his own, Hammer wanted Tony Stark to remain sober. His information network told him that Tony was drinking too hard. While Tony was held prisoner within Justin Hammer's Villa, he was granted no access to alcohol and Hammer wanted him to drink water. This was an obstacle to Tony's developing alcoholism.
- David Michelinie and Bob Layton conceived Justin Hammer as the cautionary tale of what kind of person Tony Stark might have become if he had stayed on his path as a global war profiteer. Hammer was also created as a tribute towards English actor Peter Cushing.
- 58 appearance(s) of Justin Hammer (Earth-616)
- 10 appearance(s) in handbook(s) of Justin Hammer (Earth-616)
- 4 minor appearance(s) of Justin Hammer (Earth-616)
- 19 mention(s) of Justin Hammer (Earth-616)
- 7 mention(s) in handbook(s) of Justin Hammer (Earth-616)
- 12 image(s) of Justin Hammer (Earth-616)
- 7 quotation(s) by or about Justin Hammer (Earth-616)
- 3 item(s) used/owned by Justin Hammer (Earth-616)