True name

A Tue Name is the name you are branded with since the moment you breathe life, and hold onto even after death. Each individual has only one, and when spoken, is under the complete control of the speaker. The effect of saying a true name, is similar to the effect of casting a geas. The Knower of Names can tell the names of all. The Red knight knows the true name of Tempus.

Neverwinternights
In Neverwinter nights:Hordes of the underdark, the Knower of Names can tell you the true names of your allies, enemies, and even you.

Your true name is based on your alignment.

Lawful Good: Donita'ar the Blessed

Lawful Neutral: Lysisius the Firm

Lawful Evil: Dretchen the Dark

Neutral Good: Ebela'ar the Kind

True Neutral: Neuthroxus the Fair

Neutral Evil: Nel'zeben the Selfish

Chaotic Good: Kagita'ar the Heartseeker

Chaotic Neutral: Murdus the Wild

Chaotic Evil: Ba'elzaden the Cruel

The true name of the Knower of Names: Pyreshi the Knower

The true name of Mephistopheles: Tra'axfyl the Ambitious

The true name of Cassandra: Cassanduria the Beautiful