Mongul was an intergalactic conquerer who was noted for using his tactics over his brute strength. Across the galaxy his name was feared due to his great power. His gigantic intergalactic spaceship, Warworld, was known for being holding several thousands of slaves and hosting competitions. This was often what financed most of Mongul's conquests of several planets.
As a young child, Mongul was fascinated by fights and how one animal could massacre another because of strength. It was under this ideal that he killed his brother. Growing up and becoming one of the most physically imposing creatures in the galaxy, Mongul was able to put his scientific mind to use when he created Warworld. Following his ideal, Mongul eventually killed off all members of his species but himself and his son, Jochi. The goal of Warworld was simply to prove that he was the greatest. Eventually Warworld was surrounded by the fleet of the Oblivoron Federation, and the warlord easily destroyed the planet's military. Mongul then set his sights on the Green Lantern Corps, seeing defeating the intergalactic marines as the best way to place himself at the top.
However, before he was prepared to face the Corps, Mongul arrived on Earth Prime, under hope that the planet would be able to provide him with the proper resources. The fight of the Superhero population gave Mongul his first loss, and he spent years preparing to fight back. During this time, Mongul trained and defeated several Green Lanterns. Using his alien technology to corrupt the human video gaming systems, Mongul sent the Golden Fury to the planet and upon return, defeated one of the planet's greatest heroes, the Batman. However, after Superman joined the fight, Mongul was defeated and imprisoned within the Phantom Zone. There he was trapped with the mirage that he had destroyed Earth and killed Superman, awakened only when Warworld and Jochi arrived. Watching Jochi kill every single being on Warworld, an angry Mongul proceeded to murder his own son. Recruiting the masses found in the Phantom Zone to his new Warworld, Mongul was once again dethroned as General Zod wrested control of the space station from him. Mongul was then stationed alongside Non, and when Batman led a team to the Phantom Zone the two enemies clashed, with Mongul again losing.