Anya

Raised Rabbit but ultimately gained an intense fear of rabbits
880: Cursed her unfaithful lover, recruited by D'Hoffryn to become a Vengeance Demon
Dedicated her life to punishing men, granting dark wishes to the women they hurt
1998: Came to grant a wish in Sunnydale, power source was destroyed, became mortal
2002: Left at the altar by Xander, became a Vengeance demon again
2003: Gave up her powers becoming mortal due to the guilt of her actions
Rejoined the Scooby Gang in their campaign against the First Evil
2003: Died fighting in the battle at the Hellmouth