The original Captain Marvel (Marvel) in the Marvel comic's universe.
A Kree soldier sent to the backwards planet known as "Earth" to moniter its progression. He took the cover of a deceased scientist Dr. Walter Lawson. Overtime, he developed a respect for earthlings, particularly humans, rejecting his original mission and adopting the name "Captain Marvel". His most notable feat was preventing Thanos from using the Cosmic Cube to annihilate all life on Earth.
He was exposed to carcinogenic nerve gas, and despite the best efforts of Earth and alien science, he would succumb to cancer, mourned by both heroes and villains alike. He is considered "Uncle Ben dead" at this point.
His name has been adopted by various other superheroes, currently held by Carol Danvers.