Megron

The Megron was High Lord of Chaos and Chief of the Carions.

Biography
The Megron ruled Earth for millions of years beginning shortly after its creation, when it was still a chaotic mass of molten rock.

When the Megron discovered the Fourth Doctor and Sarah Jane Smith observing the planet, he became angered at the Doctor's predictions that order, specifically an atmosphere and life, would arise out of the chaos.

The Megron encountered the Doctor twice more at intervals millions of years apart. On their final encounter, he was banished forever from Earth after being defeated by the Doctor in a telepathic battle — with his last words being "I am going, going, but I live on. Chaos can come again, come again!" (AUDIO: Exploration Earth)