Marius

Marius was a drifter who witnessed the horrors of Tristam. He follows the Dark Wanderer after the destruction of the bar he was hiding in. He then becomes a companion to the Wanderer. His sanity is questionable, as well as his courage, as he is tricked by Baal into removing his soulstone and then is unable to though the infernal gate in Kurast to go to Hell to destroy Baal's soulstone at the Hellforge.
Many years later, Baal visits Marius, now an old man, in human form in his cell in a mental asylum. He then narrates the events of Diablo II to Baal, who he mistakes for Tyrael. In the end, he confesses to Tyrael that he did not destroy the soulstone and gives it to Baal for destroying it at the Hellforge. Baal then reveals himself and kills Marius, destroying the asylum in the process.