Mongul the Elder
Mongul is an alien world-conqueror and the leader of Warworld. His brutal and merciless nature make him an enemy to Superman and a threat to the larger universe. His specialty is using the Black Mercy plants to incapacitate his opponents.
Despero is an intergalactic conqueror and enemy to the Justice League of America. He has been a member of the Injustice League, Secret Society of Super-Villains and the Time Stealers. The ruthless tyrant ruler of planet Kalanor, he possesses incredible mental powers in addition to his great strength and intellect.
Helspont is a powerful Daemonite and an accomplished conqueror. In service to the Daemonite empire he subjugated entire star systems and became a legend. His success and abilities created enemies out of his own people though, and out of fear of what he could do, he was imprisoned and exiled. His prison was the Eye, which would eventually become the headquarters of the clandestine planetary defense team Stormwatch. When Harry Tanner set off a massive explosion that ripped the Eye apart, the portion of the structure containing Helspont's cell crashed down to Earth, landing in the Himalayas. It was there that Helspont, now freed, established a new base, and it was there that he had his first confrontation with Superman.
Deep in the heart of Africa is a city hidden by mountains and illusion. Where it now stands, a meteor (or a spacecraft, depending on the account) crashed during the 19th century; its rays imbuing a gorilla tribe with hyper-intelligence and telepathy. There they now live, in an advanced society using science far beyond our own, calling the city " Gorilla City".
On an exploratory mission, their leader Solovar was captured by humans. Rather than reveal the existence of Gorilla City, he played dumb and allowed himself to be taken to a Central City circus. Grodd came after him, but not for rescue; his intent was to steal Solovar’s secret for controlling others through force of mind. He succeeded, but ran afoul of the Flash for the first time. His plan to create an army of his fellow gorillas and take over the world was foiled.
Since then, Grodd has spent most of his time imprisoned in Gorilla City, breaking out only when he has a plan ready. Often, he has gone to Central City hoping to eliminate the Flash before he could interfere with his plans. At times, he has led a political faction within Gorilla City, sometimes even becoming the dominant force.
Ocean Master is the evil half-brother of Aquaman, son of his father and another woman. Determined to usurp the throne of Atlantis, he employs piracy and terrorism to reach his goals. His powerful mystic abilities are channeled through his trident, although he also has access to technology and many other weapons.
Darkseid is the ruler of Apokolips and Darkseid's Elite and was a major player in the cosmic war that was the Final Crisis. Unto the hell that is Apokolips came Darkseid, pure hatred personified, a merciless tyrant who demanded unwavering devotion and abject fear from all his subjects. A being of unparalleled strength, Darkseid nevertheless preferred not to sully his gloves with combat unless provoked to action. His eyes emitted the formidable Omega Sanction, ray beams that could disintegrate, teleport, or resurrect depending on the dread lord's wishes. His sole mission in life was to find and gain control over the Anti-Life Equation which would give him the means to usurp all free will in the sentient universe.
Black Manta is one of Aquaman's greatest villains. His lethal high-tech suit allows him to survive underwater and adapt to any number of situations with an arsenal of destructive weaponry. Despite his prominence, Manta remains an enigmatic figure, his identity and his origins kept secret. The motivation for his villainy is a deep-seated hatred for the sea due to strong emotional reasons, and a personal vendetta against Aquaman. He has also been a member of O.G.R.E., the Injustice League, and the Secret Society of Super-Villains
Parasite is an enemy of Superman who feeds on energy by hungrily absorbing it into his body, draining all living creatures into husks at his touch. Because of the massive danger he presents to anyone he comes into contact with, he spends most of his time imprisoned in Stryker's Island Penitentiary. He has been a member of the Suicide Squad, Superman Revenge Squad and Secret Society of Super-Villains.
Eclipso is a powerful cosmic entity representing the wrath of God. Eventually he turned evil and was cast from Heaven, with the Spectre chosen to take his place. He is an entity who bonds himself to a human host using black diamonds to bring out their anger, usually taking the form of scientist Bruce Gordon. Although he is capable of bringing out the darkest evil deep in the hearts of men by his presence alone, Eclipso can be defeated by direct light.
Professor Zoom is the second Reverse-Flash, arch-nemesis to Barry Allen. Born in the 25th Century, he is a time-traveler who attempts to destroy everything the Flash has ever stood for through murder and deceit. Barry's twin Malcolm Thawne is his ancestor.
The being known as Starro the Conqueror was once a little boy named Cobi who lived peacefully along with his people (specifically his brother Andrez) on the "unremarkable" planet Hatorei. The Hatorei people lived simple lives and they had few semblances of a developed world but in one respect they were unsurpassed. Once a day the planets inhabitants would congregate in a species-wide telepathic link and open up to each other which made their society the pinnacle of ethics and cultural stability.
Now Starro the Conqueror, he used his control of the Star Conqueror species to begin a series of war of conquests. While he would enslave most foes with Star Conqueror starfish, he would grant some particularly useful opponents larger starfish to wear upon their backs and a place at the head of his armies under him, allowing them free will so long as they turned their talents towards his conquests. As his empire's expansion continued, he was able to draw power from everyone so controlled. Between his mind-controlling staroos, ever-growing strength and his still independently thinking elite, his forces were unstoppable, leading him to gain control of nine galaxies.