The Evil One ;3
Several heroes travel to Tristram, hearing rumors of a corrupting evil, vast riches, and arcane magic. The Horadrim member Deckard Cain assists the heroes in their journeys. Canonically, however, it was the playable Warrior character who seeks and ultimately vanquishes Diablo. Thought able to contend with its evil, the Warrior forces Diablo’s Soulstone into his own forehead. After returning to Tristram, the town's inhabitants celebrates their champion's victory, but the Hero returns a much changed man, haunted by Diablo's essence.
The Hero departs Tristram and travels to the East for answers to his nightmares.