Atrocitus

Atrocitus (Voiced by Jonathan Adams) is the leader of the Red Lantern Corps and the main villain in the first half of Green Lantern: The Animated series.

Much about his past is shored in mystery, but a few things stands out that his home planet, along with his wife and children were destroyed by The Manhunters. Consumed by rage over the destruction of his home and lost of his family, he blamed the Guardians for creating The Manhunters. He created the Red Lantern Corps on a ship called The Shard, which is what's left of Atrocitus homeworld. He wouldn't stop until the Guardians and the Green Lantern Corps are dead.

Trivia:
It is revealed that Atrocitus murdered Razer's lover, Illana, in order for Razer to join his cause.