The Hulk [Bruce Banner] (introduction, origin]; Rick Jones (introduction); General Thunderbolt Ross (introduction); Betty Ross (introduction)
Scientist Bruce Banner saves a young boy from being killed by a nuclear blast but absorbs deadly amounts of gamma radiation which transforms him into a monster dubbed the Hulk. Bruce Banner is scientist by day, but transforms into the Hulk once the sun goes down.
Spider-Man [Peter Parker] (introduction, origin); Ben Parker (introduction); Crusher Hogan; Flash Thompson (introduction); Liz Allen (introduction); May Parker (introduction); the Burglar
Peter Parker is bitten by a radioactive spider and gains the abilities of a spider. When he fails to stop a burglar who runs past him his uncle is killed as a result. He therefore swears never to shirk his responsibility again.