Clint Barton was orphaned at an early age when his parents died in a car accident and was sent to a children's home with his brother Bernard. He and his brother ran away to join the Carson Carnival of Traveling Wonders, and the pair worked as roustabouts. While a member of the circus, Hawkeye was trained by the original Swordsman (Jacques Duquesne) and Trickshot. Clint's life, however, would forever be changed after he stumbled onto the Swordsman counting the money he had just robbed from the carnival. The Swordsman offered Clint to become his partner in crime, but Clint rejected his mentor, sparking a fight that ended when the Swordsman left him for dead after he fell from the high wire. Barney, too, abandoned him, in disbelief that Clint passed up such an opportunity. Trickshot stepped up his role as Clint's mentor, later asking him to join him in raiding a criminal named Marko. However, Clint severely injured one of Marko's guards and discovered him to be his brother, Barney. Repelled by the consequences of his actions (and his mentor's role in prompting them), he abandoned Trickshot and parted on bad terms.
His natural archery abilities honed to an expert level, Clint wandered the country, working in various carnivals or otherwise making money out of the costume and persona of "Hawkeye". One day, when witnessing Iron Man save the lives of some people at the carnival, he decided to become a costumed crime-fighter himself. But as luck would have it, on Hawkeye's first night on patrol, he was mistaken for a criminal by the police and hunted down.
He soon met the Black Widow, who was working at the time as a costumed villain for her country, and she easily seduced the hot-headed adventurer, making him think it was in his interest to defeat Iron Man. He attempted to do so according to her prompting on several occasions, but soon wised up, regretting his decision. Instead, he hoped to join Iron Man's team of Avengers. As a way of proving himself, he broke into the Avengers Mansion and convinced their butler, Jarvis, to play the role of a victim so he could display his powers. Iron Man vouched for Hawkeye, and he joined the new line-up that included Captain America, the Scarlet Witch, and Quicksilver.
Clint continued to be an active member of the Avengers for years, with his archery skills matching the superhuman powers of his teammates. His brash attitude initially chafed under the leadership of Captain America, and, although it took some time to come to respect him, the two have become good friends. Also at first, he felt attracted the Scarlet Witch, even to the point of having trouble getting over her eventual marriage to the Vision. For years, he also continued to hold a torch for the Black Widow, until she returned to her espionage career and told him that she had never loved him (although she said that in order to keep him away.)
Hawkeye stayed with the Avengers for a long time, leaving only briefly when his temper and ego led him to believe he wasn't wanted. He returned after a short period, having joined the "non-team" Defenders in the meantime. At one point, Hawkeye was passed over accompanying the Avengers in the Kree-Skrull War due to his lack of superhuman abilities. Not one to be deterred so easily, Hawkeye took on the identity of Goliath with the use of Hank Pym's size-altering particles. He hitched a ride so as to join the team in their intergalactic adventure and maintained the Goliath identity for several months upon their return to Earth.
During his time as Goliath, Clint was approached by his brother, who had become a big-time racketeer. Barney had learned of Egghead's plans to construct an orbiting laser death-ray to extort money from the United States and came to the Avengers for help. The Avengers confronted Egghead and his allies, the Mad Thinker and the Puppet Master, but tragically, Barney died in the ensuing battle. Later, Egghead would use the Swordsman to capture Clint as Goliath, thinking him to be Hank Pym, but Hawkeye-as-Goliath soon defeated both criminals, avenging his brother at last. Soon afterward, Clint abandoned the Goliath identity but continued to serve the Avengers as Hawkeye the Marksman.
Another leave of absence was forced upon him, when, due to a type of "affirmative action", he was replaced by the Falcon to comply with the Avengers' government sanction. During this time, he eventually found employment as a night security guard for Cross Technological Enterprises (CTE). Never gone from his team for long, he soon rejoined the fold, although one particular solo adventure would have a lasting impact. His boss, head of CTE, was the villain known as Crossfire and hoped to test his ultrasonic equipment with which he hoped to turn heroes against one another, With the help of the ex-secret agent, Mockingbird, Hawkeye defeated Crossfire. The two heroes, head over heels in love, promptly got married.
At the time, the Vision was expanding the Avengers' operations, and he named Hawkeye chairman of a west coast branch of Avengers, and Mockingbird joined him as a charter member. Hawkeye led the team through several adventures, growing into a competent leader, and he even had time to embark on a series of solo adventures. During one of these latter adventures, Hawkeye had to defend himself against many costumed mercenaries and villains hoping to collect a bounty placed on his right arm. The mastermind behind it all proved to be Trickshot, now dying of cancer, and he was hoping to goad Hawkeye into killing him. Instead, Hawkeye reconciled with his former mentor and friend.
During an adventure where the team became lost in the past, his wife was involved with the death of the Old West hero, the Phantom Rider, and the situation caused the couple to split up. Shortly after, the government forced the membership of the U.S.Agent on the team, and Hawkeye quit. Both he and Mockingbird wound up investigating and leading the heroes known as the Great Lakes Avengers. Eventually, however, Hawkeye left the Midwest to rejoin the Avengers West Coast, although he never really led the team again.
Hawkeye continued to adventure with the team, even alongside his separated wife, and was present with them when Mockingbird was killed in a demonic dimension, saving her husband's life from an attack by Mephisto. Distraught, Hawkeye left the team and took a cross-country walkabout. Later, Clint was commissioned to train a group of rebels known as the Shadows along with Sundance and Striker. He attempted to keep them from killing, but on one raid Striker killed a woman and injured her fiancé, a friend of James Rhodes. As War Machine, Rhodes was surprised to see Hawkeye among the rebels, and even more so when a government backed group led by the U.S.Agent also arrived. The three were able to stop the conflict and were confronted by the mysterious Advisor.
Eventually drawn back to the Avengers' fold when the team was attacked in a plan orchestrated by Immortus, Hawkeye was present with the team when they apparently died, sacrificing themselves to absorb the energies of Onslaught. Eventually, Hawkeye and the other heroes were restored, and Hawkeye quickly rejoined the reforming Avengers.
However, Hawkeye was dissatisfied. His previous experience as a team leader left him feeling too anxious as a regular member. Hawkeye turned his attention instead to the team of reforming villains, the Thunderbolts. Sympathetic because of his own outlaw past and eager for new challenges, Hawkeye offered to serve as the Thunderbolts' new leader if they would continue fighting crime and remain reformed. During his stint as their leader, he became a friend and mentor to the group, honing their skills and greatly enhancing their reputations. He and his teammate Moonstone had even began developing romantic inclinations. The Thunderbolts soon became trusted allies of the Avengers, though Hawkeye formally resigned his membership in the latter group since he didn't want any perceived criminal association with the Thunderbolts to negatively impact the Avengers.
Unfortunately, CSA agent and former Avengers government liaison Henry Peter Gyrich targeted the Thunderbolts for assassination as part of a larger scheme to eradicate superhumans. Hawkeye and the Thunderbolts exposed and thwarted Gyrich's conspiracy, freeing Gyrich himself from the mind-controlling technology Baron Strucker had used to make Gyrich act out his anti-superhuman fantasies. Hawkeye agreed to keep the entire affair a secret in exchange for a full federal pardon for the other Thunderbolts, but a bitterly furious Gyrich refused to go along with concealing the incident unless Hawkeye went to prison for operating as an illegal vigilante with the Thunderbolts. Hawkeye agreed and was remanded to federal custody.
While in Seagate Federal Penitentiary, Barton was contacted telepathically by Mentallo, who orchestrated a break-out for Hawkeye and three others (one of which was a Mentallo-possessed Headlok). Despite their success, the inmates remained remotely "chained" to each other. The so-called “Chain Gang” reluctantly agreed to work together to search for a way to survive, deactivate their security manacles, and to search for a weapon of great power left behind by the death of the criminal industrialist Justin Hammer. Unknown to his associates, Barton was actually working undercover on behalf of the espionage agency S.H.I.E.L.D., who hoped to use Barton as a mole to track Mentallo's criminal activities. S.H.I.E.L.D. also hired the Thunderbolts' Songbird, who tracked Hawkeye and defeated his erstwhile allies. They discovered that Hammer's legacy was a biological toxin that had been ingested by every single villain who had ever worked for him and that one of the villains, Plantman, was the carrier. Hawkeye, Songbird, and Plantman began a new search for the trigger that would release Plantman's toxin. The search ended with Hammer's daughter, Justine, who turned out to be the Crimson Cowl, leader of the Masters of Evil. Hawkeye convinced several members of the Masters of Evil to side with him and Songbird against Crimson Cowl and their former allies, pointing out the dangers of the super-weapon. Hoping to throw off suspicion, Hawkeye made the villains reinvent their costumed identities, thus creating a new team of Thunderbolts. The group ultimately defeated the Crimson Cowl and her Masters of Evil, and Plantman (as Blackheath) managed to release an antidote for the toxin into the atmosphere.
Hawkeye and his Thunderbolts also helped Citizen V and the V-Battalion to help destroy their headquarters' engine of alien technology that had began distorting, In so doing, they were reunited with other the Thunderbolts, led by Baron Zemo and trapped on Counter-Earth. The two teams combined forces to shunt the alien ship from Earth. After much discussion, most of the costumed heroes and villains chose to part company. Hawkeye agreed to leave the Thunderbolts to Zemo's leadership, reluctantly agreeing that Zemo had proved he had potential to be a hero.
Hawkeye returned to the Avengers full-time. At one point, he and the Wasp had a dallying romance, upsetting Yellowjacket, and the two heroes avoided talking about the uncomfortable situation. Soon afterwards, however, the Avengers suffered a series of sudden and devastating attacks from friends and enemies alike, culminating in a surprise attack by the alien Kree. During the Kree invasion, Hawkeye suffered a mortal shot to the back. In his dying moments, Hawkeye overpowered a Kree soldier, using the soldier's jetpack to fly both of them into the Kree's command ship. Hawkeye sacrificed his life to single-handedly thwart the invasion. (These attacks were in part motivated by the Scarlet Witch, whose mind became unhinged with the magical powers she constantly felt forced to control, and it is believed the Kree invasion was all a magical construct of the Scarlet Witch.)
Hawkeye showed up alive once more in the Scarlet Witch's mutant-dominated alternate reality, with no memory of the reality before. When a young mutant gave several of the heroes the ability to remember the way the world once was, Clint and the others were horrified at what the Scarlet Witch had done. With his memory restored, Hawkeye remembered the events his own death. When the heroes confronted the Witch and her children, Hawkeye angrily shot her in the back, demanding to know why she had killed him, as he was her friend and had only love for her. One of the Witch's children made Hawkeye vanish into nothingness with just a thought. After reality was restored several heroes arrived at the ruined Avengers Mansion after a report that someone had been there, only to find Clint's costume and a newspaper cutting about his death, pinned to the ruins by Hawkeye's trademark purple arrows.
It was later revealed that Clint indeed survived and that he was the one who nailed the costume on the wall. He realized that the whole world thought that he was dead and he himself also had doubts of who he really was. In his disordered state of mind he found himself standing in front of Doctor Strange's house. He met Strange who ensured him that he was who he thinks he is and that he is indeed alive. Strange informed him of what had happened and that Wanda couldn't be found and that he thought she might be dead. Clint didn't believe this and started to search for her. He found her in Wundagore Mountain where she lived with her aunt Agatha. She didn't remember anything and didn't recognize him at all. She also told him that she had lived her whole life in that village. Clint decided to stay in the village for some time with her until he for some reason came back to the states and contacted Iron Man revealing to him that he was alive. After Iron Man had ensured that he was who he said he was he made Clint an offer to be the next Captain America. Clint even tried the flag on and got to use the original shield but he realized that it was a mistake when he met Patriot and new Hawkeye who convinced that he wasn't Captain America. Clint let them escape and gave the shield back to Iron Man and told him that he will mail the "flag" later. Not long after this Clint again found himself in front of Doctor Strange's house now seeming as though it had been abandoned and sold to a franchise company. In reality, however, it was illusion cast by Strange to hide himself and his team members from Iron Man. They decided to show themselves to Clint and after some talk and magic they decided to give Clint Ronin's costume. They then left to Japan to save their team member Maya Lopez from the Hand.