The Hulk is cast as an emotional and impulsive alter ego of the withdrawn and reserved physicist Dr. Bruce Banner. 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.