Hawkeye is the superhero alter ego of Clint Barton. Hawkeye first appeared in Tales of Suspense #57, where he took on the role of an apprehensive villain. Not long after, he'd appear again in two more issues of Tales of Suspense, then would finally join the Avengers roster in Avengers #16. He was also one of the founding members of the West Coast Avengers, and the original Thunderbolts. At various times throughout his career he's also been a member of the Defenders, along side Dr. Strange and the Silver Surfer.
Clint Barton was an orphan at a young age, and like many other wayward youngsters, he set out to work in the circus. He honed his archery skills while under the tutelage of the Swordsman and Trickshot. After realizing the duo happened to be criminals, Barton opposed the two, which lead to Barton ending up in the hospital. It wasn't until he saw Iron Man during battle that Barton decided to become the costumed hero Hawkeye.
After various mishaps, wrongful accusations, and naiveté, Hawkeye teams with Black Widow. Black Widow tricks him into trying to steal blueprints from Tony Stark, thus leading to Hawkeye seeming more and more like a criminal. Later Hawkeye applied to join the Avengers, and takes a role as a member on the new team along side Captain America, Quicksilver, and Scarlet Witch.
Aside from the times he's used Pym-Particles to become the giant hero Goliath, Hawkeye has no real superpowers to speak of. He relies solely on expert marksmanship and "trick-arrows."
Captain America (One issue)
Hawkeye has appeared in numerous games, as both a non-playable and playable character.
Spider-Man: The Video Game (Playable)
Captain America and the Avengers (Playable)
Venom/Spider-Man: Separation Anxiety (Non-Playable)
Marvel Ultimate Alliance (Playable)