Who he is: Hawkeye, a.k.a. Clint Barton
His power: No superpowers, but his mastery with a bow and arrow is so impressive that it might as well be considered one. Beyond that, superior strength and physicality.
His story: Clint Barton is a longtime agent of S.H.I.E.L.D., though when we first meet him in The Avengers, he’s almost immediately brainwashed by Loki to serve as his aid after capturing the Tesseract, though by knocking him out, Black Widow is able to clear his mind in time for him to join the team and defeat the Chitauri invasion (which is nice, since he was the one who saved her from the KGB in the first place). After that, he helped the Avengers wipe out Hydra. During the fight against Ultron, he hid the team in his home, where they learned he has a wife, Laura Barton, and two small children, with a third on the way. After that, Barton retires, though he comes back to help Steve Rogers during the events of Captain America: Civil War, even going to prison to allow Steve and Bucky Barnes to escape. Captain America returns the favor by freeing him at the end of the film.
Played by: Jeremy Renner
Currently, Hawkeye is: Possibly with Steve Rogers, possibly on his way back home.
Where will we see him next? It’s unlikely he’ll reappear until Avengers: Infinity War, due in 2018, though Renner has expressed enthusiasm at the idea of a Netflix series for his character.