Krona

Krona is a Maltusian scientist, the same species as the immortal Guardians of the Universe of the Green Lantern Corps. The selected caretaker for the emotion entities, Krona was also the being responsible for the creation of the Guantlet of Power; a gauntlet that harnesses the powers of the entities, which would later serve as the basis for the Power Rings used by the various Lantern corps. He is also the being responsible for the creation of the original Multiverse and has repeatidly attempted to destroy and recreate the universe simply to witness and document its creation.

Background
A successful maltusian scientist seeking to create intergalactic order through knowledge and understanding, Krona became consumed and sometimes blinded by his pursuit. Eventually seeking to witness the Big Bang to better understand the nature of the universe, Krona’s experiment inadvertantly caused the past and the present to interweave with each other, causing the creation of the first Multiverse as the universe replicated itself into an infinite amount of parallel universes due to the interweaving of time. In addition to this, the Anti-Matter Universe was also created, unleashing evil into the cosmos. As punishment for his meddling the other Maltusians transformed him into pure energy and expelled him from their ranks.

Vowing revenge, Krona passionately awaited an opportunity to return to his physical form and start his experiment all over again. While using Green Lantern (Alan Scott)'s magic-powered ring to return to the physical realm, he was stopped by the Green Lanterns Hal Jordan and Alan Scott and banished into his energy form again before being finally restored to his original form thanks to the lord of death; Nekron, and attempts to kill the Guardians with an army of undead at his disposal. He is again defeated by Hal Jordan and the Green Lantern Corps.

Trivia

 * Krona first appeared in Green Lantern Vol 2 #40 (October, 1965)
 * Krona was the one responsible for the Manhunters' programming glitch which resulted in the anhilation of Sector 666. He did it to prove to the Guardians of the Universe that there were flaws in an emotionless police force.