Geezer Butler
In his pre-Sabbath days, inspired by John Lennon, Butler played rhythm guitar. When Sabbath was formed, Iommi made it clear that he did not want to play with another guitarist, so Butler moved to bass. According to Butler, "I'd never played bass until I was on stage at the first gig that we played. Borrowed the bass guitar off one of my friends and it only had three strings on it."