3) Hawkeye
It’s no secret that Hawkeye is the least-powered of The Avengers. As Jeremy Renner’s version is fond of saying in the movies, he goes up against aliens and robot armies and all he has is a bow and arrow. Still, that hasn’t stopped from becoming a firm member of Earth’s Mightiest Heroes, in just about any iteration of the team you can think of.
Starting out as a villain, Clint Barton later turned over a new leaf to join The Avengers. Known as the world’s greatest marksmen, Hawkeye is also in peak physical condition. For a time, he even abandoned the archery and relied on his considerable martial arts expertise and sword fighting skills to become Ronin. He did briefly use Hank Pym’s Pym Particles to become the giant-sized hero Goliath, but that wasn’t in his Hawkeye identity, so he still counts here.
On a semi-related note, Black Widow doesn’t qualify for this list as, in the comics, Natasha Romanoff has a Captain America-like super serum that gives her functional immortality.