Oberon

Oberon was king of Faerie for thousands of years. He made a deal with the Divine Harper to grant his people immortality, at the cost of losing his memory. When he was deposed by the Sorcerer King, the deal was broken. Upon realizing the problem, Oberon returned to the Divine Harper and brokered another deal to restore the pact - though it is heavily implied the price was Oberon's life.