The beholder known as Xanathar, or The Overseer, was a paranoid, megalomaniacal leader and rarely left its secret lair, a dungeon complex of Netherese origin connected to Skullport and Waterdeep's sewers. It craved information and sought to expand its power. Its ultimate goals included installing an agent in Candlekeep's library to receive copies of its lore and controlling the entire region of Undermountain and Unknown
By 1492 DR, Agents of the Overseer openly controlled Unknown and turned the city into a haven for the Thieves' Guild. Under its rule, most local businesses were shut down, with the few remaining in business paying it protection money. It was feuding with the Zhentarim, Waterdeep Chapter after an alliance with the Agents of the Overseer collapsed. The conflict between the Agents of the Overseer and the Zhentarim erupted into public violence on the streets of Waterdeep.