Xanathar's Thieves' Guild

Xanathar's Thieves' Guild, or simply Xanathar Guild was run by a paranoid elder beholder.

Geography
This criminal/slaver network was one of the most powerful on the Sword Coast and often acted as a buffer against other evil organisations unintentionally. They had a massive stronghold on Skullport Island, but were otherwise largely active in Waterdeep.

Membership
Members of the guild were trained in stealth, discretion, and tactics with fighters, rogues, sorcerers, wizards, and experts which comprised most of its numbers. An ever-growing organization, it utilized multiple mouthpieces to protect and conceal the identity of the Xanathar. To join a member had to prove their ruthlessness, obedience, loyalty, and committing a serious crime - killing or selling a friend or family member into slavery, as well as paying 300 gp. The typical agent earned dues of 60 gp a month. Support generally came in these ways: Among the low-ranking guild members, no-one really knew who Xanathar was. Few had an inkling he was a beholder, and fewer still had spoken to him.
 * Any member given an assignment would receive a bodyguard or assistant - such as a bugbear, wererat, kenku, or gazer - with secret instructions to spy on and assassinate the agent in the case failure.
 * The guild provided safe refuges - cellars in the sewers.

Given that the faction is evil at the core, advancement through assassination is a popular "shortcut".

Notable members

 * Ahmaergo: dwarf slaver
 * Arizza
 * Avaereene
 * Colstan Rhuul
 * Shindia Darkeyes
 * Nar'l Xibrindas: drow wizard advisor
 * Nihiloor: mind flayer
 * Noska Ur'gray: dwarf enforcer