An American billionaire playboy, business magnate, and ingenious engineer, Tony Stark suffers a severe chest injury during a kidnapping in which his captors attempt to force him to build a weapon of mass destruction. He instead creates a powered suit of armor to save his life and escape captivity. Later, Stark augments his suit with weapons and other technological devices he designed through his company, Stark Industries. He uses the suit and successive versions to protect the world as Iron Man, while at first concealing his true identity.
The Black Widow's first appearances were as a recurring, non-costumed, Russian-spy antagonist in the feature "Iron Man", beginning in Tales of Suspense No. 52 (April 1964). Five issues later, she recruited the besotted costumed archer and later superhero Hawkeye to her cause. Her government later supplied her with her first Black Widow costume and high-tech weaponry, but she eventually defected to the United States after appearing, temporarily brainwashed against the U.S., in the superhero-team series The Avengers No. 29 (July 1966). The Widow later became a recurring ally of the team before officially becoming its sixteenth member many years later.
Hulk is the alter ego of Bruce Banner, a socially withdrawn and emotionally reserved physicist who physically transforms into the Hulk under emotional stress and other specific circumstances at will or against it; these involuntary transformations lead to many complications in Banner's life.