Zedd

Was a member of the Guardians of Eltar, mentored Zordon
Corrupted by the power he had sworn to protect, he chose the dark path
Tried to take the Zeo Crystal for himself, the attempt caused his skin to burn off
Sent Rita to conquer Earth, after years of her failure, he went there himself
Destroyed the power rangers command Center & their Zords
Forced to retreat when the Machine Empire arrived & attacked
Depowered & turned into a force for good by the Z-wave
Years later, his Evil half was resurrected by the necromancer Reaghoul
Destroyed the planet Rafkon, ultimately defeated & imprisoned on the planet Nibyro