Coven 13

Coven is an American rock band formed in the late 1960s, composed of vocalist Jinx Dawson, bassist Oz Osborne (not to be confused with Ozzy Osbourne of Black Sabbath), Chris Neilsen on guitar, Rick Durrett and later John Hobbs on keyboards, and drummer Steve Ross. They are recognized as being the band that first introduced the "Sign of the Horns" to rock, metal and pop culture (as seen on their 1969 debut album release Witchcraft Destroys Minds & Reaps Souls).

source: Wikipedia