Like McCartney, Roger Waters is one of the rare bassists who also shines on the mic. As a co-founder of Pink Floyd, Waters not only wrote many of the band's seminal songs, but also was the driving creative force behind the band's musically adventurous and deeply conceptual work. Speaking of which, let's take a closer look at the group's classic album The Dark Side of the Moon. Not only did that album sell 50 million copies, not only did it inspire an entire generation of musicians to expand their definition of what rock could sound like, but it also produced "The Wall," an epic song that — wait for it — just wouldn't have worked without that prowling, instantly memorable bassline. Waters may have been much more than a bass player, but at his core, he was also most comfortable with those four strings at his fingertips.