Mongul

"The strong have ever devoured the weak. That is but nature's way. Yes, I know how incredibly vast the universe is. Nevertheless, there is only so much to go around. The fewer still breathing souls there are the more there is for those of us who remain among the living. It is a simple philosophy upon which I have built my empire. I come from a long line of rulers. My predecessors' outlook was planetary, mine galactic. Leaders calculate. And death always resolves the equation."

- Mongul

Mongul is a powerful alien supervillain from DC Comics, the ruler of War-World and one of Superman's greatest foes, though he has also been seen in other media without the Man Of Steel (for example a toned-down version of Mongul was seen in the cartoon series Batman: Brave and the Bold).

Mongul is a vicious tyrant who often forces heroes and villains alike to fight for his amusement and is a shameless sadist, such contempt for innocent life has made him especially hated by Superman and Mongul is one of relatively few villains who have almost succeeded in pushing Superman into a murderous rage (others who did this were Darkseid and Lex Luthor). During Underworlds Unleashed, he was offered more power by the demon Neron. However, his pride refused him, and soon he was killed and his soul taken by Neron.

After Hal Jordan's return, it is revealed that he had a son who is also named Mongul (or Mongul II or Jr.) whom the latter arrives to earth to punish the planet for his father's failures. Despite being helped by his sister Mongal, he kills her after returning home by decapitating her with a single punch to her head.

Recently Mongul II has also become a member of the Sinestro Corps, and took over a part of the Corps after Sinestro was imprisoned. He bested Arkillo and took over Korugar as the new homeworld. Confronted by Sinestro himself during the Blackest Night, he was bested and soon defeated by having his rings overriden and stabbed by Sinestro with yellow Javelin constructs. Sinestro stated that no one, yellow ring or not, can endanger the lives of the people of Korugar.

Bronze Age
Mongul was the ruler of his homeworld before being dethroned and exiled into space by his subjects. In his debut, Mongul abducted Superman's friends (Lois Lane, Jimmy Olsen, and Steve Lombard) in order to force him to give him the keys to activate the artificial planet Warworld. Once he had the keys in his possession, Mongul attempted to murder Superman and Supergirl. However, Mongul was defeated after the heroes destroyed the device, forcing him to retreat.

Mongul later invaded Prince Gavyn, also known as Starman's, home planet Throneworld, murdering his sister in the process. He then forced Gavyn's lover to marry him in order to usurp control over the planet, and forced the resident planets to surrender under threat of Throneworld's planet-destroying weapon. Though he was defeated by Superman, Mongul then stole a Sun-Eater and attempted to devour the Earth's sun, seeking to wipe out all life on the planet. However, with the combined efforts of the Justice League and the Legion of Super-Heroes, Mongul is defeated once more.

Mongul later ambushes Superman on his birthday and ensnares him with the Black Mercy, an extraterrestrial plant that feeds off of a victim's bio-aura while trapping them in a fantasy world. While Wonder Woman battled Mongul, Batman and Robin freed Superman from the plant, leading to the Man of Steel to attack Mongul in a rage and nearly kill him, only relenting when he saw a statue of his parents. Mongul took the opportunity to try and kill Superman, but was defeated when Robin ensnared him with the Black Mercy, trapping Mongul in a fantasy world where he was the ruler of the universe.

New Age
Mongul was the ruler of War-World, during which life forms from across the galaxy were abducted and forced into gladitorial combat. Superman was transported to War-World and forced to battle Draaga, one of War-World's most powerful fighters. Superman defeated Draaga, but refused to kill him, prompting Mongul to face Superman in battle himself. Superman was teleported away from the battle by the Cleric, and War-World's citizens eventually revolted against Mongul, who was dethroned by Draaga. Mongul fled, swearing vengeance.

Mongul was eventually found and forced into service by Cyborg Superman, who promised him a new world to rule. Mongul led an invasion on Earth, destroying Coast City with carnage globes and then constructing Engine City for Cyborg Superman. Secretly, however, Mongul intended to betray Cyborg Superman. Mongul eventually attempted to obliterate the Earth, but was battled by the Justice League and ultimately defeated by Green Lantern while the Cyborg was defeated by Superman.

Mongul ultimately escaped from prison and attempted to enact vengeance upon the Green Lantern, but was surprised when the new Green Lantern, Kyle Rayner, could hurt him directly with his power ring. Mongul escaped once more, but was stopped by the Flash. He was later offered a deal by the demon Neron, but Mongul attacked the demon and was subsequently killed.

DC Animated Universe
In the DC Animated Universe, Mongul was the tyrannical ruler of the planet Warlord. To distract his subjects from the daily oppression and poverty they faced under his rule, Mongul regularly hosted gladiatorial combat, which usually led to the death of whoever lost the match. Upon capturing Superman, Mongul pitted him against Warworld's champion, Draaga, who Superman managed to defeat. However, when Superman refused to kill him, Warworld's populace begin to rebel against their ruler in favor of the Man of Steel. To counter this, Mongul challenged Superman to a match, secretly threatening Superman to deliberately lose the match or else Mongul would destroy Draaga's home planet. However, with the combined forces of Superman, the Justice League, and Draaga, Mongul was defeated and dethroned.

Returning several years later to seek revenge, Mongul ambushed Superman on his birthday and trapped him in the dream world of the Black Mercy, seeking to take over Earth without Superman to protect it, forcing Wonder Woman and Batman to take Mongul on while simultaneously attempting to free Superman from the Black Mercy. Ultimately, Mongul was defeated once more and ensnared by the Black Mercy, leaving him in a comatose state. His fate afterwards is unknown.

​Trivia

 * Mongul was co-created by Lein Wein and Jim Starlin, who also created Thanos (Marvel)