The Avengers were formed when Thor's brother Loki, opened a portal between Midgard and Jotunheim. Frost Giants began invading Earth, and only the world's greatest heroes could stop them. One by one, Iron Man, Captain America, Hulk, Thor, Giant-Man, and Wasp arrived to stop them. After the threat was averted, the six of them decided to remain a team. They elected Giant-Man as the leader, and it was his decision for the Avengers to team up with S.H.I.E.L.D., where Hawkeye was placed on their team. Later they got more members, including Ms. Marvel, War Machine, Valkyrie, and Black Widow.