Tomar-Tu is a Green-Lantern from the world of Xudar, in Sector 2813. Tomar-Tu was recruited by Hal Jordan during his stay on the Mosaic world. He was one of primary defenders of Oa when Jordan attacked the Guardians of the Universe. During the battle he was defeated and left for dead. He crash landed in the middle of a ceremony involving Jordan and two other Air Force pilots, Colonel Shane Sellers and Captain Jillian Pearlman. It was discovered by Jordan and Guy Gardner that he had been held captive by the Manhunters (along with Laira, Kreon, and others), but had recently escaped to kill Jordan in revenge.
He has later joined the Green Lantern Corps, along with his fellow Lost Lanterns, and fought against the Sinestro Corps during the Sinestro Corps War. Durings the Blackest Night, he was present on Ysmault, with the other Lost Lanterns, to retrieve the body of Laira, as they were confronted by the Red Lanterns. The skirmish ended when black power rings descended to the world, reanimating the 4 deceased Inversions, and Laira, who slashed Tomar in the chest.