Hal Jordan's enemies: Kanjar Ro
Traveling to Earth, Kanjar Ro paralyzed the entire population with his Gamma Metal Gong. He would only release the people of Earth if the Justice League went with him to fight on his side and defeat and capture his three rivals. The JLA duly obliged, but where able to turn the tables and and also defeated Kanjar Ro.
Finding an alternate way to release the people of Earth, the JLA left the four tyrants on a distant planetoid created by Green Lantern where they could do little harm. Kanjar Ro managed to escape this planet and make his way to Rann, where he found a means of giving himself super powers. On this occasion, Adam Strange, Rann's Earth born protector, teamed up with the JLA to foil Kanjar Ro's plans.
Over the years Kanjar Ro has been repeatedly defeated by Adam Strange and the Justice League. Finally, leading an army of Adam Strange's former foes, Kanjar Ro succeeded in conquering the planet Rann. At the same time his old enemy Hyathis had become dictator of Thanagar, and it wasn't long before a war broke out between the two planets. (For the first time - the Infinite Crisis would see the two planets at war again). Adam Strange became the leader of the Underground forces who battled Kanjar Ro and they were joined by Hawkman and Hawkgirl in their efforts. Eventually Kanjar Ro went to Thanagar to assassinate Hyathis himself, but he was thwarted by Hawkman.
Kanjar Ro was imprisoned on Rann until it was destroyed during the Rann-Thanagar Holy War. Kanjar returned to Dhor and became the planet's ruler once again. However, a new threat to the planet Dhor was on the horizon. Starro was amassing a legion of Starro drones to take over the Vegan System. Ro offers his assistance to the R.E.B.E.L.S. but Xylon, the Dominator member of the team, refuses to accept Kanjar's offer. Now, planet Dhor must fend for itself because General Smite, Starro's second in command is already on his way.
Fortunately, planet Dhor is saved by Adam Strange and Captain Comet. However, Strange came to Dhor's rescue because Kanjar was in possession of the Gamma Gong, a powerful intergalactic weapon and he didn't want it falling into Starro's hands.