Axl Rose holds the title for largest vocal range in known history. It raises five octaves and two or three pitches (don't know if the latter is the correct term). Rose has been known to record his extreme vocals on some Guns N' Roses songs, ranging from Mariah Carey-esque screeches on the punk rock cover 'Ain't It Fun' to guttural death metal mutters and on the epic 'There Was a Time'. What do you guys think of Rose? I think he's the greatest vocalist in history, hands down.
Fun fact: Despite Rose's reputation as a high pitched singer, he is a natural bass baritone.