I dearly hope there's a special place in Hell waiting for you Arthas.
Who: Uther the Lightbringer
Source: Warcraft III: Reign of Chaos
Notes: Uther was Arthas' mentor before Arthas went to side with the Scourge. After attempted to stop Arthas to get the urn holding the ashes of his father Terenas Menethil II of Lordaeron, Uther was killed but not before he cursed Arthas. His spirit still live on and help many heroes of the Alliance.