Atrocitus

Atros, more commonly known as Atrocitus, Atrocitus is an enemy to the Guardians of the Universe and Sinestro. He is also the leader of The Red Lantern Corps.

Backstory:
When the rogue Manhunters rampaged through Space Sector 666, his wife and kids die, he changes his name from Atros to Atrocitus, he became angry, his blood was being replaced by rage, uncontrollable anger, and became Leader and Founder of the Red Lantern Corps.