Best known as the bassist and primary lyricist for Black Sabbath, Geezer Butler is one of the most influential bass players in heavy metal. His distinctive down-tuned sound and melodic approach played an integral part in shaping the styles of lauded low-end specialists like Billy Sheehan, Iron Maiden's Steve Harris, and Metallica's Cliff Burton, among many others. In addition to his four-decade-long career with Black Sabbath, Butler has recorded and performed with Heaven & Hell, Ozzy Osbourne, and Deadland Ritual, and has released three solo albums under the moniker GZR.