Nihiloor

Nihiloor was a mind flayer who worked for the Xanathar's Thieves' Guild in the late 15 century DR, by creating and spreading intellect devourers throughout the sewers of Waterdeep.

Personality
The illithid had an alien mind and enjoyed scheming and plotting from the shadows. It considered itself Xanathar's equal but had no interest in supplanting the beholder.

Activities
Nihiloor's main activity was to create intellect devourers. It set them loose in Waterdeep, either in search for random targets to control or, occasionally, after specific targets such as members of the City Watch or City Guard. Individuals dominated by the intellect devourers then proceeded to act as spies for Nihiloor or, in specific cases, to capture and bring slaves or hostages to Skullport.