Halaster Blackcloak

Halaster Blackcloak is a fictional character in the Forgotten Realms, a popular setting of the Dungeons & Dragons role-playing game. In the setting, he is known as the infamous and powerful Mad Mage of Undermountain.

Long ago before Waterdeep existed, he arrived with his seven apprentices to make his lair in an old abandoned dwarf fortress. A wizard of undeniable prowess, he soon transformed the ancient caves into a fearsome dungeon, in fact the rumored deadliest and certainly most renowned of all Faerûn by “collecting” a huge number of extraplanar monsters and installing numerous traps and portals.

Using his magical talents, he turned Undermountain into a quasi-mythal, gaining powerful abilities and immortality within his complex. The drawback, however, was this turned him also completely mad while he was in his dungeon.

Expedition to Undermountain states that Halaster died trying to prevent an unknown magical threat dwelling (or fated to dwell) in Undermountain. Remnants of his spirit haunt his old lair, not a ghost but rather memories.