Gamemnae, also known as Gemma Cooper, is a powerful entity who is one of the former leaders of the planet Jarhanpur, a sister planet to Krypton and Daxam. She became a high-ranking member of Leviathan on Earth. After the removal of Rama Khan as the leader of Leviathan, she became its new leader. After the creation of Earth-Prime, she is also a mentor to Andrea Rojas and a board member of Obsidian North, whether she had this title on Earth-38 is unknown.
Original multiverseWhen Andrea Rojas and Rama Khan teleport to and fight at Leviathan's hideout, due to Khan being defeated by Supergirl, Gamemnae appears to break up the fight. She tells Khan that his reign is over and takes over the leadership of Leviathan as Khan tells her that this is not over.
It's unknown exactly how much of her history was changed, however in the new multiverse, she goes by the legal name Gemma Cooper and was a college mentor and friend of Andrea Rojas. While looking over her work with Obsidian North's "Collective Dream" VR lenses she convinces her to create an alternate reality for people to stay permanently that are unable to function in normal society. 
Powers and abilities
- Jarhanpurian physiology: As a Jarhanpurian, Gamemnane has special abilities.
- Extended longevity: Gamemnane is nearly immortal having lived for millions of years.
Behind the scenes
- In DC Comics, Gamemnae was an Atlantean sorceress who was born 3,000 years ago. She forcibly became the ruler of Atlantis but she later learned that Aquaman and the Justice League from the 21st century would pose a threat to her rule sometime in the future. Therefore, she formed the League of Ancients in order to defeat the heroes.