Marvel has officially debuted Hulk's dark new alter-ego "Titan" in the pages of Hulk #6, which is no on sale from Marvel Comics. This climax of the "Starship Hulk" story arc by Donny Cates sees Bruce Banner and his "Starship Hulk" construct stumble upon the alternate reality where Banner's Gamma experiments were a major success (no accident) and gave America the unstoppable WMDs of mutated Hulk versions of major superheroes and figures (named "Abominations") – a power controlled by President Thunderbolt Ross. Well, when the Marvel 616 Universe Banner piloted Starship Hulk into this reality, it sparked the unleashing of Titan!
WARNING: Hulk #6 SPOILERS Follow!
The 'United States of Gamma' reality that Starship Hulk stumbled into immediately rocked that world, as Ross and co. saw a version of Banner/Hulk they didn't control, and was significantly powerful. "The Abominations" were dispatched to tear Starship Hulk apart, forcing "Captain Banner" in the diver's seat of Starship Hulk to push the "engine" of his creation (i.e., a raging Hulk locked in a Danger Room) beyond the safety limits.
Internally, "Engine Hulk" is set loose against the very gods and cosmic beings of the Marvel Universe, letting loose a level of rage we've never seen from him, while Bruce's "driver's seat" is hijackjed by the entity that's been masquerading as Betty Ross during this entire arc. "Betty" reveals itself to be the entity Titan, now fully unleashed by the level of rage and power Hulk has achieved. Externally, Hulk transforms into a huge, monstrous beast that looks like DC's Doomsday.
This "Titan" form of Hulk not only tears through The Abominations like they're nothing, it is seen to be siphoning gamma energy from the creatures it's devouring. The entity piloting Titan wrestles all control away from Banner – but Banner had a failsafe: releasing "Engine Hulk" from his cage!
Engine Hulk's untethered rage is still the greatest power the character has – and not even Titan can stand up to it. Engine Hulk annihilates the evil entity internally, effectively rebooting Starship Hulk and allowing Captain Banner to perform quick repairs to Hulk's physical body. Starship Hulk works with the Banner of the Gamma USA reality to stop President Ross's Gamma Bomb from dropping on thousands of innocents and leaves that reality through the wormhole that brought him there.
It's not made explicitly clear if Titan has been expelled for good from Bruce Banner/Hulk – but we wouldn't bet on it. "Starship Hulk" hung its entire thematic premise on challenging the idea that Hulk is the manifestation of Bruce Banner's repressed anger and ID; it posited that Hulk is actually protective measure, filtering Bruce Banner's malevolent genius through a form that can channel it properly. Titan is, therefore, marked as being "Hulk's Hulk" – i.e., a manifestation of Hulk's malevolent rage once it spikes past a certain level. That's a concept Marvel can revisit for many years to come, as Hulk is now an even bigger worldly (or multiversal) threat than ever before.
Hulk #6 is on sale at Marvel Comics.