The Xanathar was one of most infamous beholders of the Realms and the crime lord of the Xanathar Thieves’ Guild in Skullport.
The Eye’s primary base was in the southern half of the third level of Undermountain near Skullport in a fortified complex, but it also maintained an extensive lair in the sewers of Waterdeep, linked to its other lair by a keyed portal.
Xanathar was believed to have been killed when the Xanathar Thieve’s Guild was destroyed. However, recently a new Cult of Xenathar has sprung up, attempting to assassinate Laeral Silverhand, the open Lord of Waterdeep. After investigation it was discovered a beholder was leading the operation, however this beholder turned out to be nothing more than an animated zombie beholder. Whether this beholder was the animated remains of Xanathar himself, or Xanathar managed to avoid death and is attempting to rise again, only time will tell.