What is the name of the final boss in Guitar Hero III?

The final boss in Guitar Hero III is Lou the Devil. In the single-player Career mode, Lou is the last of the game's three guitar-battle opponents, following Slash and Tom Morello.

Lou is introduced as the band's manager, but the story eventually reveals that he is a demonic figure who has claimed the musicians' souls. The climactic battle takes place in Hell and uses a metal arrangement of “The Devil Went Down to Georgia,” originally recorded by the Charlie Daniels Band and reworked for the game by Steve Ouimette.

The battle differs from a normal song because both players can trigger attack power-ups against one another. Lou's especially punishing attacks include Death Drain, which steadily lowers the player's Rock Meter. If the player defeats him, the game proceeds to the ending sequence and the player must finish the remaining section of the song.

A common mix-up is answering “Satan” or “the Devil.” Those describe Lou's role, but Lou the Devil is the character's canonical name in Guitar Hero III.