What is Hawkeye's super power?

Question

In the movie Avengers, Hawkeye seems like a filler character. He isn't in any of the previous movies, and there's no story about him at all. Does he just have super vision? Does he have a back story about it?

Answer 1

Hawkeye, like Natasha Romanoff aka Black Widow, is a human, except he is a lot more skilled than most. He doesn't have super powers like Captain America, Thor, or Hulk, but he is a master assassin.

He does make a cameo in Thor uncredited as Clint Barton, which I think you can say is a precursor before his role in Avengers, though he didn't have as important a role that Black Wdow's character had in Iron Man 2

In case you might be curious about his skillset you will find this excerpt from wikipedia enlightening:

While Hawkeye has no superhuman powers (with the exception of the period when using Pym particles to become Goliath), he is at the very peak of human conditioning; he is an exceptional fencer, acrobat and a grandmaster marksman, having been trained from childhood in the circus and by the criminals Trick Shot and Swordsman. This includes considerable strength, as a supervillain found out when he tried to use the superhero's 250 pounds-force (1,100 newtons) draw weight bow and found that he could not draw back the string to launch an arrow.[98] Hawkeye has also been thoroughly trained by Captain America in tactics, martial arts, and hand-to-hand combat. Hawkeye excels in the use of ranged weapons, especially the bow and arrow, and carries a quiver containing a number of customized "trick arrows". In his role as Ronin, Barton shows great proficiency with the katana and other melee weapons. He has gained a reputation for being able to "turn any object into a weapon", and has been seen using items such as tin plates, coins, sticks and other debris to great effect against his enemies. Hawkeye is also known to use a "Sky-Cycle" as his mode of transportation. The Sky-Cycle is modelled after a commercial snowmobile and is fitted with anti-gravitational technology. It is voice operated and has an auto-pilot steering system. The original Sky-Cycle was custom made for Hawkeye by Jorge Latham while he was employed by Cross Technological Enterprises.3 Latham was later employed by the West Coast Avengers and built several more

Answer 2

In the comic Ultimate Comics Hawkeye #2 there is a spot where it mentions he has higher than normal rod cells. Normal person has hundered and fifty million rod cells and hawkeye has closer to 4 hundred million. Also the muscle around his eye allow for orb distortion giving him the ability to change focal length. This could be argued as a mutation similar to those in X-Men. Which would make him a superhuman/superhero and not just a normal human.

Answer 3

Hawkeye is far from a filler character. He's been in every Avengers lineup in every continuity (Comics, Animated, Movie ... etc). Movie-wise, this isn't his first appearance either. He first appears in the Thor movie (the same way Black Widow appears first in Iron Man 2).

Like Black Widow, he doesn't have any super human powers and his past is shrouded in mystery (at least in the movies universe). Although one can argue that his skill with the bow and arrow is super-natural.