Lou is a devil type of character playable in Guitar Hero III: Legends of Rock, and is the last boss guitarist. Lou is unlockable once you beat him in a Guitar Battle at the end of any career on any difficulty. His name is a reference to Lucifer. You also unlock his Guitar called the "Obliviaxe", which looks like a skeleton corpse (the headstock is a horned skull, the fretboard is a spine, and the body is a rib cage). He is also playable in Guitar Hero: Aerosmith
In single-player mode, Lou originally poses as the manager of the player's band. He signs the band after the performance in Mitch's Moose Lounge, unknowingly giving Lou possession of their souls. Lou reveals himself after the gig at Kaiju Megadome through the contract in red printing at the bottom claimed "Your soul is mine", along with flared red eyes. He also reveals himself as the god of the Rock Underworld, Hades.
In the Co-op story, Lou appears after the band members are arrested because of the fire inadvertently started by their encore performance of Cities on Flame with Rock and Roll in their Backyard Bash. Lou makes a deal to set the band free as long as they perform for the prison inmates. Doing so, as soon as they step out of Shanker's Island, Lou drags them down to his domains.
He is basically the Guitar Hero version of Satan.
Lou, in his human form, also appears in the Guitar Hero III tutorial, antagonizing the God of Rock.
In Guitar Hero: Aerosmith his guitar can be purchased for $500.
Lou is not playable in Guitar Hero World Tour, but he appears in various cutscenes.
In Guitar Hero: Smash Hits, he imprisons the God of Rock, takes on his guise, and then recruits Johnny Napalm, Axel Steel, Lars Umlaut and Casey Lynch to collect souls with an "artifact" while on stage in several famous venues, but then fails when the band gets ripped off by him and claims the artifact back and rescues the God of Rock, who then takes them to Quebec City.
In the PlayStation 3, Xbox 360, and PC version of the game, Lou only has one outfit in the game called "Thick Izzy" (which looks like the gigantic being in the background of Lou's Inferno).In Guitar Hero: Aerosmith Lou has many new outfits as well.
- In the Guitar Hero III Control Panel's Texture Explorer, the texture files for Lou contain the word "satan."
- When beating Lou in the Guitar Battle of GH3, Lou repeatedly does an animation of him slowly looking down and lowering his guitar.