The Arcane Brotherhood is a mercantile company and wizards' guild that operates out of the Host Tower of the Arcane in Luskan. The organization is shrouded in mystery, as even it's most high-ranking members are unknown. It is known however that their goals are political and economical control of the North. They are widely recognized, unofficially, as the de facto controllers of Luskan. Many prominent members of Luskan society are, one way or another, affiliated with the Arcane Brotherhood. The current, or at least last known, Archmage Arcane is Arklem Greeth.
Many powerful groups, such as the Zhentarim, the Cult of the Dragon and the Red Wizards of Thay have attempted in infiltrate the Brotherhood, to no avail. They continually clash with the Lords' Alliance, especially alliance member Neverwinter, with the frequent feuding between the two city-states.
The Arcane Brotherhood, and some of its members, play a role in both Neverwinter Nights games, and the player even visits the Host Tower in the first game.