Kroloteans
The Kroloteans are a fictional extraterrestrial race existing in the DC Universe. They first appear in Green Lantern #4.
Fictional character biography
Native to the planet Krolotea in Space Sector 2812, the Kroloteans are an insidious species who perform genetic experiments on subjects in an unethical attempt at creating a scientifically advanced race of warriors to sell to the highest bidder. They have no compunctions with manipulating the evolution of other species as part of their experiments, so long as it produced highly destructive "weapons" which they could sell to their clients. They are responsible for the experiments done on Hector Hammond, Black Hand, and The Shark.The Green Lantern Venizz uncovers a Krolotean concentration camp where she liberates its prisoners who were subjected to various experiments. Among the many victims was Tagort, whose body and strength were overgrown due to the Kroloteans' experiments.
After investigating a human who was experimented on by the Kroloteans, Hal Jordan is contacted by the Belle Reve prison authority, which informs him that Hector Hammond has information on the event. Going to the prison, Jordan bargains with Hammond, who reveals that the Kroloteans previously gave him and Black Hand their powers.
In the meantime, the Kroloteans had found another test subject in a shark which they genetically engineered and evolved into an anthropomorphic form. This attracts the attention of Hal Jordan, who battles Shark until the Kroloteans capture them both. Jordan thwarts the Kroloteans, who are handed over to Venizz and Tagort to be brought to justice.
At least one member of the species known as Gleen was selected as a member of the Sinestro Corps and assigned to Space Sector 312. Amongst his species, Gleen is considered the cruelest and most twisted. He is killed by Alpha Lantern Varix when he attempts to break Sinestro out of his prison transport.