In the DC Universe Imperiex is a Malevolent entity, featured in the Our Worlds at War crossover. Imperiex Prime is also called, The Devourer of Galaxies. He is the embodiement of entropy, signaling the end of existence. First appearance in Superman #153.
He was first mentioned in the Superman titles 2000, when Mongul, the son of the deceased villain of the same name, arrived on Earth saying Imperiex had destroyed Warworld and was heading for Earth. He convinced Superman to help him fight Imperiex. However it transpired that the huge alien entity they had encountered was just a probe; Imperiex Prime himself was a much larger and more powerful being. He had detected imperfections in the fabric of the universe, and his ultimate plan was to destroy it and create a new, perfect one. To do so he headed for Earth, the planet which holds the Universe together, to start a new Big Bang from there.
Before arriving to Earth, Imperiex erased countless other planets. Kalanor, Karna, and Daxam are three known planets destroyed in his cataclysmic campaign. Whole galaxies where also targeted for demolition as Imperiex Prime sought to fulfill his destructive destiny, obliterating one universe so that a new one would be born! After destroying Karna, Imperiex arrived at Almerac the home of Maxima, and not only destroyed Almerac but Hollowed the whole galaxy. After this, the survivers of the dead worlds, Brainiac-13's Warworld, Apokolips and Earth formed a coalition (Darkseid as its commander) to fight against Imperiex Prime and his probes. Finally arriving to the Milky Way Galaxy, Imperiex started sending in numerous Imperiex-Probes. On Earth several of his machine-colony "Hollowers" destroyed Topeka, Kansas (as well as seven other places) when they began to dig into Earth to ready it for Imperiex's final demolition, which would also cause a new Big Bang.
President Lex Luthor rallied other superheroes, the military of the U.S. and other countries such as Pokolistan, together. Furthermore, Luthor had decided that Superman alone did not have enough power to lead a strike force and arranged for Doomsday to be released from captivity and brainwashed to believe all Imperiex drones to actually be Superman. They fought the Imperiex probes and managed to destroy several until Imperiex himself was finally drawn to them, within second's Imperiex slew Doomsday in a cascade of cosmic fire. Imperiex then turned to Superman and blasted him but was saved by Darkseid. With the destruction of Imperiex's ship, he was battling all of the coalition alone. In a gamble that paid off, Earth and Apokolips fired there full might at Imperiex along with Kismet joined with Superman managing to crack open Imperiex's impenetrable armor but not before Imperiex killed Kismet. Brainiac 13 then revealed his true agenda and began merging with Imperiex's celestial energies. With the coalitions last hope, Superman with the help of the other heros managed to send both Imperiex Prime's and Brainiac's consciousness back 14 billion years to the Big Bang. Imperiex Prime realised that the imperfection he had detected was himself.
The Imperiex War was not won without cost. At least 8 million people on Earth died during the war. The total number dead in the DC Universe is stated to be countless. Several heros also died including Queen Hippolyta, Maxima, and General Sam Lane (Lois Lane's father) all died defending Earth. Aquaman, Doomsday, Guy Gardner, and Steel were all presumed dead, but later turned up alive for different reasons.
