What Happened To Every Version Of The Hulk?

After Banner mistakenly thought that Tony Stark was responsible for him being turned into the Hulk, the scientist decided to make a new Hulk persona - seemingly just to spite Stark.

In order to prove a threat to Tony, Bruce ups his intake of the Extremis virus - which he was using in small doses to repair brain damage - creating Doc Green, a super-smart version of the Hulk, who is mercifully smart enough to recognise that Iron Man was not responsible for the Hulk being created in the first place.

After a series of adventures - and creating a serum which he used to depower several other creatures created via Gamma radiation - Doc realises that the virus that upgraded his intelligence is a temporary fix, and thus returns to being the regular Hulk.