Volthoom was the First Lantern.
When Krona conducted his mad experiment to see the beginning of the universe, Volthoom arrived in Universe 0 from Universe 3 and informed the Guardians of the Universe that he came in peace. Showing the Guardians the Emotional Spectrum, Volthoom bathed in the First Light of Creation and became the First Lantern by putting on the very first Power Ring. When the Guardians probed him to share his power with others, Volthoom refused and killed millions. Volthoom was even able to resist and defeat the Manhunters, prompting Volthoom to realize that the Guardians had turned on him.
Locked in the Chamber of Shadows by the Guardians, Volthoom was guarded by the Templar Guardians who desired to keep his power away from the universe. After millions of years, Volthoom was removed from his prison by the Guardians and vowed to kill them. However, before he could escape, the Guardians began to siphon out his power to create the Third Army.
When the Guardians fought against the Green Lantern Corps, however, they accidentally shattered Volthoom's prison and freed him. Reincorporating the Third Army within himself, Volthoom imprisoned the Guardians of the Universe in his house on Maltus.
Locating Sinestro on Korugar, the First Lantern made his way there and attacked him. Forcing Sinestro to fight him, Volthoom manipulated him and destroyed Korugar. Making his way to Oa, Volthoom proceeded to mentally torture the Guardians before fighting John Stewart, Guy Gardner and several other members of the Green Lantern Corps. After easily defeating them and even the Red Lantern Corps, Volthoom faced and endured the dual onslaught of the Blue Lantern Corps and the Star Sapphire Corps. With the different warrior sof the Emotional Spectrum convening with Mogo, Volthoom was weakened for the first time in battle. Then attacked by Sinestro, Volthoom's second fight with the Korugaran was halted by the Indigo Tribe who summed Hal Jordan and the Black Lantern Corps.
Eviscerating the Black Lanterns, Volthoom began to exploit Hal's emotions to look for a time when he was consumed by fear. Using those emotions to tear at the fabric of the Timeline, Volthoom was once again attacked by Sinestro, who had now bonded with Parallax. After being placed at a momentary disadvantage, Volthoom defeated Sinestro for a third time.
However, Volthoom was now brought face to face with Nekron. After Hal Jordan stripped him of the Emotional Spectrum and expelled his power ring to Universe 3, a mortal Volthoom was reaped by Nekron.