Zzzax

Zzzax is being of pure energy, and only been able to be seen by the Hulk.

Origins
Origins are unknown.

Attacking New York
When the Hulk seemingly went on arampage in New York, it was actually him trying to stop Zzzax from draining all the energy from New York. Hulk teamed up with Spider-Man, who was being interviewed by Mary Jane at the time, and they overloaded him with energy.