The broader history behind the alien robot species covered in this article was introduced in Justice League of America #140 (March 1977), in a story by Steve Englehart and Dick Dillin.
The Manhunters were the first attempt of the Guardians of the Universe to create an interstellar police force that would combat evil all over the cosmos. Their name and much of their code of behavior was modeled by the Guardians of the Universe on the Manhunters of Ma'aleca'andra (Mars) millions of years ago (This creates an apparent chronology problem, since the Manhunters were created many millions of years ago, while the Green Martian race came into existence from the Burning Martians only about 20,000 years ago). For thousands of years, they served the Guardians well. However, the Manhunters became obsessed with the act of "hunting" criminals. Their code, "No man escapes the Manhunters" (corrupted from the original), became more important to them than seeing justice done.
Eventually, the robots conspired to rebel against their masters, but the Guardians defeated and destroyed most of them. Those that survived hid away on many planets, slowly rebuilding their forces and spreading their beliefs to others. Since then, the over-riding goal of the Manhunters has been to take revenge on the Guardians, as well as on their replacements, the Green Lantern Corps.
The Manhunters were discovered by the Justice League who seemingly defeated the Manhunter's leader, the Grandmaster. One of their human pawns, Mark Shaw, adopted a new identity as the costumed hero, the Privateer. However, he was later discovered to be a criminal posing as a hero.
Years later, it was revealed that the Manhunters not only still existed, but had infiltrated the lives of most superheroes with their agents. They even managed to infiltrate the Olympian Gods, one of their number posing as the goat god Pan, as shown during the Challenge of the Gods storyline. They revealed themselves when a Guardian and a member of the Zamarons tried to evolve some humans into becoming the next Guardians of the Universe, during what became known as the Millennium crisis. On this occasion, there was a massive counterstrike operation by the heroes against the Manhunters, and it seemed that the Grandmaster had finally been destroyed, along with their hidden home planet. Former Privateer Mark Shaw readopted his identity as Manhunter in the wake of the battle, seeking to redeem both the name and himself.
Kyle Rayner encountered the Manhunters not long after Hal Jordan's destruction of the Guardians and the Central Power Battery on Oa. The first of which encountered a still inexperienced Kyle Rayner and was almost able to defeat him using brute force until Kyle used his wits to outsmart and decapite it(Green Lantern Vol. 3 #117). The next time, multiple Manhunters appeared. They were all sentient, individuals, and captured Kyle in an attempt to use his last remaining Green Lantern ring for their purposes. They failed and Kyle managed to escape(Green Lantern Vol. 3 #129-131).
When the Manhunters were replaced by the Green Lantern Corps, they retreated to Biot, their homeworld in Sector 3601, an uncharted area of space incapable of sustaining organic life. Hank Henshaw, the Cyborg Superman, came to Biot and became the Manhunters' new Grandmaster. He used his mastery over machinery and Kryptonian technology to upgrade the Manhunters with organic enhancements. They seem to have rebuilt the first Central Power Battery originally destroyed by Hal Jordan (under the influence of Parallax). Henshaw decided not to interfere in the reformation of the Green Lantern Corps after an encounter between a Manhunter and Green Lanterns Hal Jordan and Guy Gardner.
The Manhunters have recently resurfaced as part of the Sinestro Corps. They carry miniature yellow Power Batteries inside them which are used by the Sinestro Corps members to charge their yellow power rings.
In Green Lantern: Secret Origin storylines, this revision of Hal Jordan's beginnings, it is revealed that the Manhunters suffered a programming glitch that caused them to wipe out all life in space sector 666, believing it to be evil. It was this event that gave rise to the Five Inversions, the only survivors of the massacre, who vowed to make the Guardians pay for what their creations had done.
During the events of Blackest Night, it is revealed that Amanda Waller and King Faraday have a deactivated Manhunter in their possession, having recovered it from the Belle Reeve swamp after the Millennium event (which the Suicide Squad had a hand in stopping). Waller sends the Manhunter to Belle Reve in order to assist the Secret Six and the Suicide Squad in their battle with members of the Black Lantern Corps. Waller ultimately uses a self destruct mechanism to destroy the Manhunter, unleashing an explosion of Green Lantern energy that eradicates the Black Lanterns.
It was eventually revealed that the programming glitch the Manhunters suffered was caused by Krona to prove to the other Guardians of the Universe that there are flaws in an emotionless police force.
The New 52
While running from the Alpha Lanterns, John Stewart and Guy Gardner find dozens of deactivated Manhunters in the Guardian's Ring Foundry. They re-energize the robots using the Foundry essence in order to fend off the Alphas. However, during the fight, the Manhunters are accidentally fused in a massive bio-mechanic monster.
The Manhunters have had a mixture of oaths over the years: "No evil escapes the Manhunters!", "Death to the Green Lantern Corps!", and "No man escapes the Manhunters!"
Manhunter technology has been used in the creation of the OMAC drones. The Kryptonian technology was incorporated into the Manhunters by Hank Henshaw on Biot, which enabled them to use the Central Power Battery on Oa as a power source for the Manhunters.
Originally the Manhunters used special energy pistols which were charged by the Green Lanterns which they carried.
The Manhunters have appeared in the Justice League episode "In Blackest Night" voiced by James Remar. Like their comic counterparts, they were the first before the Green Lantern Corps. However according to the Guardians, "they couldn't understand the subtle gradations between good and evil" (probably meaning draconian justice), and as such were reprogrammed for other tasks such as hunting and guarding. Though the Manhunters did not overtly express resentment for this demotion, they began secretly plotting their revenge against the Guardians for their perceived betrayal. The Manhunters bring Green Lantern John Stewart to trial for accidentally destroying the planet Ajuris 4. Unknown to the masses, the planet's destruction was faked with the help of Kanjar Ro as part of the Manhunters' plan to overthrow the Oans and take the Corps' power source, which they believe is rightfully theirs. Their gambit successfully draws five of the Guardians away from Oa to testify for John, as well as several unassigned Green Lanterns, leaving Oa severely weakened when the Manhunters attack in force. The Justice League clears John's name and then aids in defeating the Manhunters, assisted by the Corps. The lead Manhunter manages to absorb the power of the Central Battery, shedding his metallic form and becoming a giant energy being. John recites the Green Lantern oath while absorbing the energy of the battery, and by extension the Manhunter, into his ring. He then expels the evil of the Manhunter and restores the Central Battery. This was based on the comics story "No Man Escapes The Manhunters," which appeared in Justice League of America #140-141 (1977).
The Manhunters appear in the Green Lantern: The Animated Series, voiced by Josh Keaton. They are seen in a flashback in the episode "Reckoning", detailing the history of the Red Lantern Corps, and are noted to have slaughtered Atrocitus' race, leading to his transformation into the first Red Lantern. In the episode "Regime Change," Hal Jordan presents this information to the Guardians, initially believing it to be a lie. However the Guardians then shamefully reveal that they were indeed responsible for the creation of the Manhunters, and that the machines had massacred a number of innocent planets due to their inability to interact with emotional beings. The second half of the first season shows the Manhunters are being rebuilt to act as the Anti-Monitor's foot soldiers. According to both the Guardians and the Manhunters themselves, the cause for the destruction was the Manhunters viewing all emotion as the source of evil and thus seeking to exterminate it.
The Manhunters are mentioned at the end of Green Lantern: Emerald Knights. When the Green Lantern Corps are out to build a new planet, Hal mentions to Arisia Rrab about how he took on an army of Manhunters.
The Manhunters appear in DC Universe Online, voiced by David Jennison. They assist the Sinestro Corps with their fight against the Green Lanterns. Some broken Manhunters were rebuilt into remote fear generators to boost the power of the Sinestro Corps' power rings.
The Manhunters were the main antagonists in Green Lantern: Rise of the Manhunters, which was set in the same continuity as the Green Lantern live-action film, voiced by Fred Tatasciore. They having allied with Amon Sur- who resents that his father's ring went to a primitive like Hal Jordan rather than himself- in an attempt to acquire the yellow fear energy that the Guardians have acquired in the distant past and use it as a power source for themselves.