Hulk

Real Name: Dr. Bruce Banner
AKA: N/A
Powers: Transforms into a green, super strong, impervious beast with a greatly diminished intellect when angered, strength increases with further rage, genius level intellect when not the Hulk.

Transformed into the Hulk after being exposed to a gamma bomb explosion while saving a teenager, Rick Jones, from the same blast. Banner is mild mannered and a pacifist while Hulk is consumed by anger. Banner doesn’t have control over when he is the Hulk and when he is himself. Banner has a genius level intelligence and while he is the Hulk is immensely strong and generally impervious to harm. Originally grey, Hulk is now green, usually wearing purple pants or trunks. Modern Jekyll & Hyde/Frankenstein.

Hulk joined the Avengers as a founding member, being the unwitting pawn in Loki’s scheme against Thor which eventually lead to the formation of the team in order to combat the god of mischief (Avengers #1). During his time on the Avengers Hulk repeatedly comes into conflict with his fellow Avengers and as a result leaves the team (Avengers #2). The Avengers spend considerable effort attempting to bring Hulk back into the fold, if only to keep his unpredictable nature under control. Hulk has managed to evade this fate so far (Avengers #3, Avengers #5, Fantastic Four #25/26, Avengers #17). Later, the Avengers would send Spider-Man after the Hulk as a test to determine Spider-Man’s worthiness to join the team. Fortunately for Hulk, Spider-Man decides that Hulk should be left alone (Amazing Spider-Man Annual #3).

After Hulk’s initial transformation, Rick Jones chooses to stay around and help look after him and does so until leaving in an attempt to join the Avengers as Captain America’s new sidekick.

First appearance: Incredible Hulk #1
Joined Avengers: Avengers #1