The Hulk is cast as an emotional and impulsive alter ego of the withdrawn and reserved physicist Dr. BruceBanner. The Hulk appears shortly after Banner was accidentally exposed to the blast of a test detonation of a gamma bomb he invented. Subsequently, Banner will often involuntarily transform into the Hulk, depicted as a giant, raging monster, leading to extreme complications in Banner's life. In Hulk: The Incredible Guide, Stan Lee revealed that the Hulk was a combination of Dr. Jekyll and Mr. Hyde, and Frankenstein.
While the coloration of the character's skin varies during the course of its publication history, the Hulk is most often depicted as green. As the Hulk, Banner is capable of immense feats of strength, which increases with his feelings of rage and anger. Anger is a commontrigger of Banner's transformation. However, any significant emotional stress can do the same; for example, terror when he is in mortal danger. A common storyline is the pursuit of both Banner and the Hulk by the police or the armed forces, due to the destruction he causes.