Hammond is a petty criminal on the run from the law when he discovers the fragments of a strange meteor in the woods (later retconned as part of the same meteor that lands in Africa, super-evolving Gorilla Grodd and the other gorillas of Gorilla City). Observing that radiation from the meteor has caused the nearby plants to evolve rapidly, Hammond decides to kidnap four scientists and expose them to the meteor on a remote Island. The radiation causes their intellects to evolve, but also has the side effect of sapping their wills. Hammond is able to force the scientists to use their heightened intellect to create amazing new inventions, which Hammond sells for his own profit.
Hammond rapidly becomes a rich celebrity due to the wealth he has acquired. Green Lantern Hal Jordan asks his friend and mechanic, Thomas Kalmaku, to take on the role of the Green Lantern while Jordan investigates Hammond. Jordan creates a duplicate power ring and costume for Kalmaku to fool Hammond, and tells him to fly above Coast City so it would be thought Green Lantern was there. The scientists tried to use a device to bring this Green Lantern to them, but the ring was first pulled off his finger and fell on the Island, where Hammond found it. Unaware of the impersonation, Hammond steals his ring and turns Kalmaku into a chimpanzee. Jordan confronts Hammond personally in a battle of power rings that ends only when the charge of Hammond's ring runs out, allowing Jordan to capture him and restore Kalmaku and the scientists. He removed the scientist's memory of their knowledge, and got rid of the inventions as well, feeling humanity should advance more steadily.
Hammond returns in Justice League of America #14 (September 1962), where he has managed to escape from prison and deliberately exposes himself to the meteorite. The radiation causes his brain to grow to enormous size, granting him psionic powers as well as immortality in the process. He captures Green Lantern from a De-memoriser invented by Amos Fortune which he had supplied to various villains, but was later captured. Unfortunately, his body becomes immobilized and he loses the power to speak. Trapped in a motionless state, Hammond is still able to use his psionic powers to control the minds of others. He attempts to steal the Green Lantern's ring, but Jordan manages to command his ring to drain itself of power when it leaves his finger, after which Jordan renders Hammond unconscious.
Hammond is responsible for the creation of the second Royal Flush Gang in Justice League of America #203 (June 1982). Hammond and the Gang are defeated when Dr. Martin Stein, one half of the superhero Firestorm, subdues Hector on the astral plane.
He was involved with erasing the world's memories of the JLA in Justice Leagues.
In addition to battling Hal Jordan, Hammond has also fought Alan Scott as well as Kyle Rayner.
Following the 2004-2005 miniseries Green Lantern: Rebirth, in which Hal Jordan was resurrected, vindicated for his past crimes and returned as the star of the Green Lantern core series, Hammond reappeared as one of his adversaries. Recently, after his capture and further experimentation by the gremlins, the aliens which sent the meteor that gave him his powers, he seems to have recovered the ability to speak without using telepathy.
Hammond appears in Infinite Crisis: Villains United special, in which he is broken out of prison along with several other supervillains.
Hammond appears in the 2008 storyline Green Lantern: Secret Origin, a re-telling of Hal Jordan's first days as a Green Lantern. In that storyline, Hammond aspires to be Carol Ferris' boyfriend, feelings that are not reciprocated by Ferris, who merely went out to one dinner with him for business purposes, as he is a private consultant for Ferris Aircraft. While inspecting Abin Sur's crashed aircraft, Hammond is affected by the meteorite fragment used as a power source in its reactor, which results in an increase in his brain size and telepathic abilities, with which he learns Jordan is a Green Lantern. He attempts to use his telepathy to keep Hal from using his ring, but is thwarted by Sinestro. It is revealed that Hammond wants the power of a god in order to gain revenge on Hal Jordan/Green Lantern.
Hammond's telepathic thoughts are shown from Belle Reve Prison, stating "It has Parallax", after an unknown force pulled Parallax away. Afterwards, Krona helps Hammond get out of prison, to pursue the entity trapped inside Larfleeze's lantern. Hammond attacks Larfleeze and Hal Jordan, and during the fight manages to swallow Larfleeze's battery, allowing the entity, Ophidian, to possess his body just as Parallax possessed Hal's. The battle with Ophidian does not go very well for Hal or Larfleeze. While fleeing Ophidian, Larfleeze admits that he was not entirely honest about his ownership of the orange lantern and that he and Ophidian have a rather antagonistic relationship, however he is quick to blame Ophidian for starting whatever it was that came between them. Ophidian states that Larfleeze was the only being in the universe capable of resisting his temptations thereby allowing Larfleeze to subdue him and become Agent Orange, and now it's Larfleeze's turn to be subdued and used by Ophidian, Ophidian then attempts to devour Larfleeze but he is saved by Hal. After that the desires of Hector begin to override those of Ophidian and he leaves to search for his ultimate desire "Carol Ferris".
Ophidian would later apparently reassert its hold on Hector as he was seen joining Krona, and even helping the renegade Guardian of the Universe discover the location of the Butcher with its disruptive powers, and was last seen returning with Krona to Ryut where he will begin purging the universe of all emotionally unbalanced beings.
Hector's fate afterwards remains unknown as the Orange Battery is seen in the Book of the Black which prompted Larfleeze to try to recover it only to be trapped himself in the Book and Ophidian is seen without its host, launching along with the other entities and Krona an attack on Oa, where it possessed a Guardian of the Universe.
Hammond in his mutated state exhibits genius level intellect, potent telepathic and telekinetic abilities, and on occasion displays the ability to absorb and mentally redirect Green Lantern's emerald plasma. In some incarnations, his body has atrophied to the point where he cannot walk and he has to strap his head to a chair to support its weight.
As the host of Ophidian, he has access to the powers that an Orange Lantern has, without needing an orange power ring to access them.
In the alternate timeline of the Flashpoint event, Hector Hammond did not become a villain from a meteorite fragment. Instead, Hammond works as private consultant of Ferris Aircraft with his test pilots Hal Jordan and Carol Ferris. While inspecting Abin Sur's crashed aircraft, Hammond did not trust Abin Sur and believes him to be preparing an alien invasion. However, the engineer Thomas Kalmaku told him to rebuke his statement. Later, Hammond designs the aircraft into the F-35, and it is ready to take off and assigns the pilot Hal Jordan to it.
Captain Carrot and His Amazing Zoo Crew
The 1980s series Captain Carrot and His Amazing Zoo Crew presented the parallel Earth of "Earth-C-Minus," a world populated by funny animal superheroes that paralleled the mainstream DC Universe. Earth-C-Minus features "Hector Hamhock," a pig counterpart of Hammond whose nemesis was the heroic Green Lambkin.
Hector Hammond is set to appear in Green Lantern: The Animated Series voiced by John DiMaggio.
Peter Sarsgaard played Hector Hammond in the live-action film, Green Lantern directed by Martin Campbell, as the secondary antagonist. Differing from the comic book origins slightly, Hector Hammond is an average biology teacher who was an old friend (yet also a rival) of Hal Jordan's along with Carol Ferris, and also the estranged son of United States senator Robert Hammond. He has been in love with Carol since they were children. In the movie he could talk even with his bulbous cranium, unlike the comics. He was summoned by the DEO (mainly by Hammond's father and Dr. Amanda Waller) to conduct an autopsy of Abin Sur due to his father's influence. However, his rather estranged relationship with his father (who thinks he wastes his life away with his current job), as well as the influence of Parallax's DNA causing his head to grow larger while also granting him the ability to read minds and move objects with his thoughts, resulted in his being driven insane, eventually killing his father by burning him in a chamber. After his infection by Parallax, Hammond appeared to have difficulty moving, wheezing as he breathed and walking rather slowly, to the point that he was shown using a wheelchair in his final confrontation, referencing the comic incarnation's inability to move. He later abducts Carol with the intention of infecting her with a DNA sample of Parallax and making her like him. Hal defeats him by pretending to give him the ring in exchange for Carol's freedom, only for Hal to reveal that he retains control of the ring even when it is on Hammond's finger as the ring chose him rather than the other way around. When Parallax arrived on Earth, Hammond was subsequently killed by Parallax after he failed to kill Hal Jordan.