Born nearly at the beginning of time itself, Agamemno and his father began conquering planets as soon as their birth. They claimed planets and stars as their own and ruled them harshly. Those who chose to side against them were brutally defeated. After spreading their empire throughout the universe, Agamemno's father met his demise from a rebellion and Agamemno fled, vowing revenge. Over time, Agamemno evolved to a state of being capable of controlling the inanimate and transfer consciousness amongst organisms. He then went out and conquered billions of cultures in an attempt to find the ultimate source of power that he could use to rule the universe. After a millennia, he finally discovered that there are three items of power in the universe, and when united together, they give the bearer ultimate power. He then sought the means to collect these items and reclaim his father's rank, for his powers were minuscule compared to that of his father. While seeking for answers, he came across the answer to his problems in the form of the Justice League while they were stuck in a world not their own. Realizing that none of them would do as he wished, he found other applicants that were not bound by a moral code. Offering Lex Luthor and the soon to be Injustice League the earth for their cooperation. Luthor agreed and they set their plans into motion.
After carefully planning a crisis in each of the Justice League's hometowns. When each of the heroes of that area came to the rescue, they were ambushed by at least two members of the Injustice League and Agamemno transferred the consciousness of the hero into his arch-villain. The transfer of minds goes as follows: Batman and the Penguin, Superman and Lex Luthor, the Flash and Mr. Element, Green Lantern and Sinestro, Green Arrow and Felix Faust, Black Canary and Catwoman, the Atom and Chronos, Martian Manhunter and Doctor Light, and Aquaman and Black Manta.
After forming this team, they all set out to find the items of power spread throughout the universe. He was in a group with Superman/Lex Luthor, Atom/Chronos, Green Arrow/Felix Faust, and Aquaman/Black Manta. Their target was Brainiac's crashed ship where they destroyed all of the defenses and the Atom took a diamond from a shrunken portion of Krypton. Then they left for Thanagar to gain the Absorbascon. Agamemno then impersonated being a member of the Justice League, but was confronted by Sinestro/Green Lantern. After being hit by an immense energy beam from Sinestro, he reconstructed himself as many smaller versions of himself and helped the retaliation against Sinestro, but Sinestro made all of the heroes and villains in their own bodies. Then, after taking the Absorbascon, he and his group of villains fled Thanagar in the new Sinestro's energy field and disabled a legion of Green Lanterns that fought them.
After deciding on going to Rann to form the weapon, they went there and conquered it with ease. After gloating in their power for a little while, the new Seven Soldiers of Victory came to combat them. In this battle, Agamemno entered and controlled the jet pack of Adam Strange and disabled him until the weapon was finished. He then attempted to enter and absorb the power of the weapon, he realized that he was betrayed by Lex Luthor and was seemingly destroyed.
After a long and difficult battle between the Justice League and the Secret Society of Super-Villains, the heroes, altered by a transformation dial, defeated the villains. Then Agamemno made his move and animated the weapon to be a part of his body with the power battery as his chest and battled the new Justice League, but was hit by the full power of the Green Lantern Corps, which was revived by the heroes of Earth. Then Martian Manhunter, with his new powers, teleported inside of the new Agamemno and stole the jewel from Krypton and the Absorbascon. After being severely weakened by the loss of these items, the Green Lantern Corps crushed him and imprisoned him inside the power battery, never to return again. Not even after the later destruction of the Power Battery, thought it's possible he was destroyed by Parallax.
- Unique Physiology: A being of pure energy.
- He can transfer consciousness amongst living beings, swapping their bodies. 
- Flight: He can travel in the form of pure energy and achieve FTL speed. 
- Electrokinesis: He can short out electrical machinery with a gesture.
- Possession and Molecular Reconstruction : Agamemno's essence can inhabit any matter or object, and recreate his body, becoming a living facsimile made of that material.  Due this ability, Agamemno is immortal.
- Agamemno has the knowledge of billions of alien worlds. 
- In Silver Age Vol 1 1, Agamemno told to Luthor that a mindscan revealed the JLA would oppose to his conquest, but the entity learned about the team by one of his alien slaves and Kanjar Ro , then maybe Agammeno was lying about have mind scan powers.
- It was revealed in the JLA storyline Tower of Babel (also written by Waid) that the body swap by Agamemno led Batman to develop a number of contingency plans to take down the JLA and other heroes should they go rogue.
- 7 Appearances of Agamemno (New Earth)
- 1 Images featuring Agamemno (New Earth)
- Quotations by or about Agamemno (New Earth)
- Character Gallery: Agamemno (New Earth)
This character is or was primarily an enemy of the Justice League, in any of its various incarnations. This template will categorize articles that include it into the category "Justice League Villains."