37. Nova (Richard Rider) - 428 points (10 first place votes)
Richard Rider was created by Marv Wolfman and John Buscema to basically be the Spider-Man of the 70s. Like Peter, Richard was a sort of everyman, only Richard's power came from the Nova Corps, where he was chosen (at random) to be Earth's representative in a large intergalactic police force, much like the Green Lantern Corps.
Nova fought the good fight for a few years, until the Corps was disbanded. Years later, Richard's powers were awakened by Night Thrasher, who recruited Richard to join the New Warriors, which is where he served for many years.
More recently, Nova rejoined with a newly reformed Nova Corps, just in time for the rest of the Nova Corps to be murdered during an attack by the forces of Annihilus. Richard was forced to absorb the "World Mind," which was the basis for the Nova Corps' power. He then became the most powerful member of the Nova Corps.
Nova used this power to lead the forces of good against Annihilus...
After Annihilation, he became basically a one-man Nova Corps as he set out to return the Nova Corps to their previous glory. Sadly, while protecting our universe from an invasion by an evil alternate cancerverse, Richard was killed.
36. Winter Soldier (Bucky Barnes - 436 points (7 first place votes)
Created by Joe Simon and Jack Kirby, Bucky was Captain America's young partner during World War II.
Phased out for a short time after the war, when Cap made his return in the pages of Atlas Comics' Captain America, Bucky was right back along with Cap, smashing commies.
When Marvel brought Cap back in the pages of the Avengers, however, it was sans Bucky. In one of the earlier retcons in Marvel history, Bucky now died back during World War II, in an explosion that left Captain America thought dead, as well.
Decades later, in the pages of the current Captain America series, writer Ed Brubaker revealed that Bucky had, in fact, survived and was revived by the Russians, who gave him cybernetic implants and brainwashed Bucky into becoming a killing machine for them. He also trained the operative, Black Widow, for the Russians.
They would send Bucky on a mission and then put him into suspended animation until he was needed again - this allowed Bucky to remain a mystery, as people looking for a young man in one year would not still be looking for a young man five years later, which is when he'd be unfrozen for his next mission. This is how he got the name the Winter Soldier, because they would basically just freeze him between missions.
Bucky eventually broke free of the brainwashing, due to the help of Captain America...
After the seeming death of Captain America, Bucky took over as Captain America temporarily, until his past actions as the Winter Soldier became public and he was forced to quit as Cap and return to being the Winter Soldier (this was also due to Bucky nearly being killed during Fear Itself). Most recently, Bucky discovered that Nick Fury had been secretly protecting Earth from outside alien invasions for decades. Bucky ended up taking Nick's place as the new Guardian of Earth. I suspect he will be returning to Earth soon, though, especially with the new Captain America movie coming up soon (in which the Winter Soldier will feature prominently).