Here's Marvel's top character who was on the outside looking in....
51. Captain Marvel (Mar-Vell) - 126 points (1 first place votes)
Created by Stan Lee and Gene Colan, Captain Mar-Vell was a Kree warrior sent to spy on Earth. However, he grew to dig Earth, so helped defend some humans from a Kree robot. They heard the robot call him Captain Mar-Vell, so presumed he was a new hero called Captain Marvel.
He fought the good fight for awhile before Roy Thomas and Gil Kane revamped him as basically a cosmic Captain Marvel (the Fawcett one). Rick Jones put on some nega-bands, and when he clanged them together, he would switch places with Mar-Vell, while the other one would be stuck in the Negaverse.
This was the status quo for awhile, until Jim Starlin split the two up, and had Captain Marvel become the Protector of the Universe. This was how things went for awhile until Mar-Vell ultimately died, due to cancer that he developed after being exposed to "Compound 13" by the villain Nitro.
Recently, Mar-Vell was plucked from the time stream, seemingly healthy, but in actuality, he was taken from time AFTER being exposed to the Compound, so Mar-Vell knows that he only has a finite amount of time left before the cancer takes him, so he is making the most of his renewed time living.
Here is why my pal Cayman voted for Mar-Vell...
I have to be honest, a good part of my love for Captain Marvel comes from my appreciation of his most memorable costume. Mar-Vell cuts a fine figure in the bold red and blue, combined with the iconic image of his star emblem and the shining Nega-Bands. He just looks damn cool and heroic, like the best superhero ever.
Beyond that, I think he reflect a nice evolution in the space or "cosmic" character, beyond the pulpy Adam Stranges and Flash Gordons of the past.
Finally, I love him because he's not a freakin' Skrull. Boo-yah!