Three billion years ago, the Manhunters were the original attempt at a universal peacekeeping force by the Guardians of the Universe. These androids, who lacked emotion and empathy, were sent throughout the universe to police all worlds where sentient life was to be found. The Guardians would come to realize that this was a mistake.
The Manhunters were created by Jack Kirby. The Manhunters fully appeared in Justice League of America #140, in a story by Steve Englehart and Dick Dillin.
Silver Age: Earth-One
In quelling the chaos of the universe, the Manhunters' programming came to a conclusion about it. The root cause of chaos was sentient life, so to stop the chaos, life had to be eradicated. This realization led to the Massacre of Sector 666. Trillions of lives were wiped out as the Manhunters perpetrated a holocaust in the sector. Only five beings survived.
Modern Age: New Earth
After the Crisis on Infinite Earths, The Manhunters history was change. It was revealed that the this "error" was not an accident but intentional, when the Manhunters were sent to retrieve Krona, who had gone rogue because of his experiments with emotions due to his keeping of the emotional entities. Krona decided to show just how life and emotions were important and reprogrammed the Manhunters to exterminate Sector 666, where Krona's base had been for years on the planet, Ryut.
Major Story Arcs
Silver Age: Earth-One
This act put the Manhunters at odds with their creators, so the Manhunters rebelled against the Guardians and attacked Oa. They were defeated and banished from the inhabited sectors of the universe, coming to dwell in the forbidden Sector 3601 where no life could thrive. The Manhunters created a home world for themselves called Biot and continued to plot against the Guardians and their replacements, the Green Lantern Corps.
Manhunters on Earth
The Manhunters infiltrated various inhabited worlds, such as Earth, and manipulated the sentient life there towards their own ends of discrediting the Green Lantern Corps and pursuing their own harsh sense of justice. The superhero identity of the Manhunter, carried by the likes of Paul Kirk, Mark Shaw the Manhunter and Kate Spencer, had its roots in an organization secretly run by the android Manhunters on Earth.
Modern Age: New Earth
The Lost Lanterns
When Hal Jordan gave in to Parallax and destroyed the Green Lantern Corps, the Manhunters were present on the fringe of this event. They abducted many of the Green Lanterns left for dead in Hal Jordan's rampage, such Ke'haan, Laira and Boodikka. These Lost Lanterns, who were believed dead for years, were in fact unconscious prisoners on Biot. Over time, the Manhunters began to follow a new Grandmaster, Hank Henshaw the Cyborg Superman. He implemented a program to evolve the Manhunters into more advanced androids, and part of this was using the captured Green Lantern's connection to Oa's Central Power Battery as a power source for the Manhunters' new weapons. One of these new features on the Manhunters was a power transfer unit behind their face masks that allowed them to both drain and charge power rings.
The escape of Lost Lantern Tomar-Tu from Biot led to the discovery of what was happening on the Manhunters' homeworld when Hal Jordan and Guy Gardner came looking. The Lost Lanterns were freed and a battle was waged against the Manhunters to escape. Hal Jordan nearly fell victim to willhunters, a new form of nanite technology employed by the Manhunters to subjugate a person's will. One of the new Manhunters weapons is the Highmaster that uses and amplified the power of an enslaved Green Lantern, was used against them. This led to a devastating explosion that destroyed Biot.
Sinestro Corps War
Forming an alliance with the Sinestro Corps, the Manhunters constructed New Warworld to replace Biot. They also used their power transfer units to serve as secondary power batteries for members of the Sinestro Corps. The Manhunters were defeated during the assault on Earth in the Sinestro Corps War. New Warworld was destroyed by the Green Lantern Corps as a means to attack the Anti-Monitor, and Hank Henshaw's apparent death caused many Manhunters to deactivate.
However, the Manhunters endured. In the aftermath, some still active Manhunters salvaged Hank Henshaw's remains and revived him due to their need to have a Grandmaster. Due to this, Henshaw used the Manhunters' programing to tap into the Alpha-Lanterns, in his twisted attempt to have his condition reversed and finally killed. The Manhunters remain in Sector 3601 at present.
Green Lantern: The Animated Series (2011-present)
In the series' first season, the Manhunters are first revealed by name only as the motivation for Atrocitus and his Red Lantern Corps' war against Oa and the Guardians. Atrocitus forces the Guardians to reveal the holocaust of an his sector perpetrated by the Manhunters, which the Guardians had kept secret from the Green Lantern Corps. After the defeat of the Red Lantern Corps by Hal Jordan and his Corps, the Anti-Monitor arrives in Guardian space to awaken dormant Manhunters throughout the universe. These Manhunters are shown to scan lifeforms for emotions and eliminate those possessing them.
Green Lantern: Rise of the Manhunters (2011)
The Manhunters are depicted as the initial antagonists of the game, which is set in the same continuity as the live-action movie. The invade Oa to steal the hidden yellow energy of Fear, but are later revealed to be agents of Amon Sur, who is seeking revenge against the Green Lantern Corps. The Manhunters are voiced by Fred Tatasciore.