A comic book supervillain, owned by DC Comics. Hammond made his first appearance in "Green Lantern #5" in 1961. He was created by writer John Broome and artist Gil Kane.

After finding a mysterious meteorite that appeared to have caused surrounding vegetation to evolve at an accelerated rate, Hammond kidnapped four scientists and exposed them to the meteorite. While they evolved faster and faster, Hammond used their superior brains to create incredible new inventions and turn himself into a wealthy celebrity. When Green Lantern noticed that Hammond's specialties matched with the specialties of the four missing scientists, it set up a confrontation that resulted in Hammond's defeat and imprisonment.

After Hammond escaped from jail, he used the meteorite to evolve himself, emerging as a short skinny guy with a pencil-thin mustache, a really oversized cranium, and powerful psionic abilities. After tangling with and getting stomped by the Justice League of America, Hammond altered the meteorite so that it would make him immortal -- however, in exchange, Hammond would become almost completely paralyzed. He had to travel around in a fancy floating chair. He spent most of his career as one of Green Lantern's archenemies, trying in vain to get his hands on either more samples of the meteorite or Green Lantern's power ring. He has also taken on Green Arrow, the Flash, Black Canary, the Elongated Man, Firestorm, and other members of the Justice League. He often worked in secret, using his vast mental powers to attack his enemies from afar.

When Hal Jordan became the supervillain Parallax and later died, Hammond's interest in supervillainy seemed to diminish. He is currently incarcerated under heavy security and powerful psionic dampeners. He occasionally participates in a supervillainous scheme, but he hasn't been a real threat to anyone in years.

Research: http://www.glcorps.org/hecthamm.html