Green Ghost's origin is unknown. The only thing known about him is that he is African American, and somehow acquired an amulet that, when digested, turns him into an intangible green entity. He was killed by Omni-Man, as well as his entire Guardians of the Globe team.
Powers & Abilities
Upon ingesting a small, jade colored amulet of unknown origin, the young man who would become the Green Ghost would undergo a transformation altering his body's physical appearance, seemingly generating a green aura emanating from within him. When in his Green Ghost form, his facial features were obscured to the point of being unidentifiable. As the Green Ghost he possessed the ability to become intangible at will. He was capable of reducing the mass of his atoms to practically zero, yet have them retain their chemical properties and volume.
By fine tuning these atomic forces so that they applied to other atoms in his body and not to the sub-atomic structures of the world around him, the Green Ghost could pass through solid matter like so many neutrinos, retaining his form while still capable of conscious thought and action. He could become weightless and intangible, unable to be touched by solid matter.
The Green Ghost was able to generate small, green hued, billowing cloud like constructs that defied gravity, floated in the air and appeared amorphous yet were capable of supporting the full weight of an adult human male standing on them. The cloud forms retained their shape as long as the Green Ghost willed them to exist, dissipating when he had no futher use for them.
The Green Ghost could fly by altering his mass at the sub-atomic level to create changes in inertia. The Green Ghost was able to mentally control this on a bodily level, so that all his atoms could be given a net gain in inertia in just one direction. This allowed his body to fly at very great speeds simply by willing it. A visible green energy contrail was left behind him while in flight. He was also capable of withstanding the great extreames of temperature caused by the build up of friction within the atmosphere and surviving without difficulties in the vacuum of outer space.
The Green Ghost would revert back back to his human form after regurgitating back up and out of his body the amulet he had ingested to trigger the initial transformation.