Mephistopheles

Mephistopheles is the Lord of the Eight Hell, Cania, and is a rather cunning and power hungry archfiend. In NWN Hordes of the Underdark he sought to usurp Asmodeus, Lord of the Ninth Hell and ruler of the Nine Hells of Baator, by relocating to the Prime Material Plane and turning it into the Tenth Hell. Asmodeus barred the Archfiends (rulers of each Hell of Baator) from going to the Prime Material Plane to stop just such an occurence. The player ultimately either forces Mephistopheles to return to Cania and never leave again; or join the player by the power of his true name obtained from the Knower of Names (Mephistopheles' lover whom he trapped due to the threat she posed knowing the True Names of all things, found by the player through the aid of her sister the Knower of Places who knew where she was imprisoned); or forces Mephistopheles to die by use of his True Name although the Lord of Cania cannot truly die and reforms in Cania and takes back control of the Eighth Hell; or forces Mephisopheles into a partnership where he serves faithfully as an equal and the player prospers from the union; or the player forces Mephistopheles to become his/her lackey and Mephistopheles serves by the power of the use of his True Name and tries to trick the player at some stage like he did to the Valsharess who tried to enslave him, only the player thwarts him and humiliates him for his failure.

Mephistopheles has goat like legs, big devilish horns, is red coloured, has a devil trident, and uses the strategy of slaying races then raising them as slaves to fight in his army as a means of conquest. As such his personality is untrusting, sadistic (he likes to make others suffer), power hungry, and bullheaded. It is ultimately his arrogance and inability to trust his true love that leads to his undoing.