Anti-Monitor

The Anti-Monitor was a supremely powerful being who was created eons ago by Krona capable of converting anything into antimatter for his consumption, devouring trillions of planets in his insatiable hunger. He fought the Green Lantern Corps and was decapitated by Aya who merged with his body. His head survived on Ranx until Aya tracked it down for the time travel technology in her crusade to unmake all life.

Origins
Eons ago the Anti-Monitor was created on the planet Maltus by a renegade Guardians of the Universe named Krona, who was obsessed with creating a being so powerful it could do anything, even time travel. However the Anti-Monitor conceived its superiority and broke free of his creator's control. Krona was able to banish the Anti-Monitor into another universe which he eventually nearly entirely consumed, before he tricked Nigel Fortenberry into a deal in which the latter opened a rift that allowed the Anti-Monitor to return.

Reactivating the Manhunters
He arrived on the junkyard planet Biot, where he demolished a spacecraft and activated an anti-matter pulse that soared throughout the universe, which activated dormant Manhunters on various planets across the galaxy. He then created factories to reproduce an army of Manhunters and scattered them to the vast reaches of space, to aid him on his quest to destroy the universe.

After the Green Lanterns Hal Jordan, Kilowog and Tomar-Re destroyed the factory on Biot with the help of Aya. The Anti-Monitor revealed himself and told them about his plan of using the Manhunters. He confronted them in battle. He easily overpowered them, which made the Green Lanterns flee, but before they could escape, he blasted Hal Jordan through the portal from which he originated.

After some time while the Anti-Monitor continued his never-ending hunt for matter, he came across the entrance of Frontier Space, the Maelstrom. The Anti-Monitor started dissolving the Maelstrom and encountered the Interceptor crew again, but they served no opposition to his immense powers. After Aya saved Razer from several Manhunters, the Anti-Monitor unleashed a ray of anti-matter which hit Aya—who dissolved in the hands of Razer. Before the Anti-Monitor could kill Razer, the latter was saved by Hal and Kilowog with the Interceptor. He was than confronted by guardian Scar who was seemingly vaporised and than consumed the red lantern fortress Shard while his enemies fled.

Defeat
Seemingly unstoppable, the Anti-Monitor begun cleaving through the Red Lantern armada to devourer their planet before destroying Oa. However after Razer told Aya who had survived his ray he shut down all emotion and only focused on the task at hand, Aya, heartbroken, absorbed all of the energy from the Interceptor and became a missile directed at the Anti-Monitor, blasting off his head and hijacking his body, becoming the "Aya-Monitor".

Return and final Destruction
The Anti-Monitor's consciousness survived in his head, which found its way to Ranx where it took control of the planet's systems. Hal, Kilowog, and Razer tracked it down but so did the Aya-Monitor. Anti-Monitor's head knew what she is after and attempted to make an alliance against the organic lifeforms, but Aya simply tore apart the head and took the device that would allow her to time travel, seemingly destroying the Anti-Monitor for good.

Physical appearance
The Anti-Monitor is an humongous being. He has a dome-shaped head with small shiny blue rectangular eyes, he has the primary color blue, grey joints and a golden pattern on his body.

Abilities
Anti-Monitor possesses a great deal of power, powerful enough to dissolve an entire universe. Notably, his Anti-Matter manipulation. With it he can consume matter into himself. He could conjure his abilities into a Anti-Matter pulse able to reactivate dormant Manhunter robots, without it being detected by any outside force. He could also use his abilities to create an energy beam created entirely of Anti-Matter. With it easily smashing through Hal Jordan's construct shield. Along with his Anti-Matter manipulation, Anti-Monitor is immensely strong in terms of his durability. Surviving a head-on energy ray from the Interceptor, that had previously demolished an entire factory. The Anti-Monitor has the ability to fly and survive in space.

It was stated by the science director, that the Anti-Monitor has the ability to travel through time. The Anti-Monitor can survive for long periods of time, as he was created eons ago.

Background Information
In the DC Comics, Anti-Monitor was a powerful being that existed within the Anti-Matter Universe. In the main universe from which the DC Comics regularly take place in, the Anti-Monitor was born on one of the moons as an excess of great energy taking form. In his debut appearance, he served as the main antagonist of the 1985 DC Comics miniseries Crisis on Infinite Earths. While he debuted in the book's second issue, he was not full seen until the series' fifth, in order to keep him a mystery. During the book's yearlong run, he destroyed countless alternate universes and caused the deaths of several major heroes. Anti-Monitor was ultimately destroyed by the Superman of Earth 2 after a long and protracted battle. In the summer of 2007, Anti-Monitior was resurrected and returned after a near two decade absence from publication in the storyline "Sinestro Corps War".