John Jameson is an astronaut who worked as Captain America's pilot for a while.
Before working for Cap, John once found a red jewel on the Moon, which turned him into a werewolf known as the Man-Wolf. He was turned back to normal by Spider-Man.
Astronauts were known as heroes before the arrival of superheroes, so John accepted to work as Captain America's pilot to know how these new heroes worked.
When Dredmund the Druid used Jack Russel's blood to have a lycanthropy serum created, John was one of the people kidnapped as test subjects, and Dredmund also restored the red jewel to use it on himself. Captain America heard about werewolf sightings and decided to investigate, but was captured and also turned into a werewolf. "Capwolf" was thrown into a pit where he fought and defeated the leader of the pack of werewolves imprisoned there. As new leader, Cap led these werewolves against Dredmund, while the former leader of the pack used the serum on Dr Nightshade to force her to make an antidote.
After Dredmund was defeated, the former pack leader was turned back to normal, and Cap found out he was John. After everybody was turned back to normal, John resigned as Cap's pilot.