NOTE: This article is about the incarnation of Justin Hammer from the Marvel Cinematic film series. The mainstream version can be found here: Justin Hammer (Marvel).
I took stuff, how does that make you feel? Does it make you feel bad? Good, BECAUSE THAT'S HOW I FEEL!!
~ Justin Hammer to Ivan Vanko
What I saw you did to Tony Stark on that track, how you stepped up to him in front of God and everybody, that was... WOW!
~ Justin Hammer explains how he was impressed by Vanko's intimidation and destruction at Monaco
Justin Hammer is a recurring antagonist in the Marvel Cinematic Universe, serving as the secondary antagonist of the 2010 Marvel film Iron Man 2, a minor antagonist in the 2014 short film All Hail the King and a background antagonist in Season 1 of Marvel's Luke Cage. He is Tony Stark's business rival and the owner of Hammer Industries. He was also created the Judas Bullet that Diamondback attempts to use to kill Luke Cage.
In that version, Justin Hammer was portrayed a little different compared to the comic book version: Justin appeared to be younger than Tony Stark instead of being older, he whined when he didn't get his way, and appeared to be less intelligent.
Hammer was one of Tony's rivals. He owned Hammer Industries, a company that made weapons similar to those of Stark Industries, but he was not a match still for Tony's company and therefore worked with Thaddeus Ross to develop a single pilot close-quarter combat vehicle with full protection and attack capabilities to discredit Tony Stark's Iron Man, but his claims of it being invulnerable was quickly proven wrong as it was shot down by Congolese Army in a hostile territory, which only served to make Iron Man more popular as Stark successfully rescued the pilot.
Clearly displeased, Hammer continued his work on discrediting Tony Stark by attempting to use prototypes of the Arc Reactor for the purpose of creating a new version of the Iron Man Armor, to little avail, as all of the prototypes failed, even at one point leaving the tester's spine severely damaged. This would doom Hammer when he was called in as an expert during the senate committee meeting to prove that Tony's ego and monopoly of his armor was dangerous. Although at first Hammer put up an impressive struggle by arguing that all Stark's efforts as the Iron Man were not good enough to protect the world, noting that due to the creation of Iron Man, there would be threats which Stark would not be able to foresee, claiming Stark keeping the armor was selfish and dangerous, and Stern, the one who hired Hammer in the first place, then strengthened Hammer's words by showing there were many attempts from the enemies of America to replicate the armor and therefore meant the Iron Man Armor should be under Hammer Industries's watch, Tony simply responded by revealing to the senate Hammer's failure and that he had injured many in his attempts to replicate his tech, utterly humiliating him and causing his weapon contracts to be suspended.
Furious and backed to a corner, Hammer resolved to extreme measures he and his assistant Jack witnessed Iron Man fight Whiplash, Hammer was impressed with Whiplash and planned to break him out of prison, while at the same time place a fake Whiplash to take his place so that they could perform a fake death.
Hammer and Whiplash made a deal with each other that if Ivan made a huge army of drones (known as Hammer Drones), they would use them to put an end to Tony's career. What Hammer didn't know was that Whiplash was planning to turn against him and destroy Tony with the drones.
During the unveiling of the Hammer Drones, Hammer is confronted by Tony, who has known of Hammer's true allegiance with Whiplash. However, Whiplash activates the Hammer Drones to attack the entire area, forcing Tony to use his Iron Armor to fight back. When Pepper Potts (Tony's girlfriend and temporary CEO of Stark Industries) found out that Hammer was working with Vanko, she called the cops on him.
Natasha Romanoff also forced Hammer to reveal Whiplash's current location at Hammer's building, where she finishes off several of Hammer's guards before finding out that Whiplash has escaped to fight Tony. Following Whiplash's death and the destruction of the Hammer Drones, Hammer is arrested for his crimes, and he vows revenge on Pepper for this.
All Hail The King
In the short film, Hammer is held a prisoner in Seagate Prison. During the end credits, he is seen watching Trevor Slattery (the actor who had been hired by the deceased Aldrich Killian to impersonate the Mandarin) in the prison cafeteria being admired and fawned over by other inmates. Unlike the other inmates, Hammer remarks that he doesn't understand Slattery's appeal and isn't impressed with him at all.
Hammer, although not to the same level of Tony Stark, was still an exceptionally intelligent individual with superb engineering and businessman skills. This is shown by how he had developed weapons of sufficiently high level to impress the US Government and replace Stark Industries when they stopped making weapons for the government and even before that had already been a strong rival of Stark Industries with several military and government contacts.
Hammer giving Vanko a tour inside Hammer Industries HQ.