Cole Turner

Sent by the triad to destroy the Charmed Ones but fell in love with Phoebe
Belthazor was vanquished, turning Cole into a human
Possessed by the Source of All Evil, vanquished by the Charmed Ones &sent to the Demonic Wasteland
Absorbed all the demonic powers he could until he was powerful enough to escape
Joined the Avatars, altered history but was vanquished by the Charmed Ones
Ended up in a cosmic void between life & death as punishment for his crimes