Al'Diabalos, the Lord of Terror, known more commonly amongst the citizens of Sanctuary as Diablo, is one of the three Prime Evils, alongside his two older brothers Mephisto and Baal. Despite being the youngest of the three, he has become the most powerful of all, capable of causing terror at the very mention of his name alone.
Born long ago from the heads of the dragon Tathamet, Diablo's personal methodology pertains to not only instilling but also fostering not only fear but also terror, allowing it to fester in the hearts of men. He does this simply for its own sake and, surprisingly, is not actually specifically seeking either conquest nor power. Diablo is the master of the Realm of Terror, a sparsely populated region of the Burning Hells -- this is because not even demonkind can stand its unrelenting torment. At least one member of the Horadrim considered Diablo, while not the most intelligent of the brothers (that honor was bestowed upon the eldest brother, Mephisto), he was absolutely the most creative, even to the extent of being referred to as an "artist of terror".
- Diablo (primary antagonist) (1st appearance)
- Diablo II (primary antagonist)
- Diablo III (primary antagonist)
- World of Warcraft (cameo)
- StarCraft II: Wings of Liberty (cameo)
- Heroes of the Storm (playable "hero")