Black Babbath, formally known as Earth (I think) which was a blues band, invented the Heavy Metal genre with the debut of their second album, Paranoid. Even if you listen to the song, Black Sabbath, which was on their first album, Black Sabbath, is more bluesy than metal. I swear the intro sounds alot like the start of ghostbusters, only slower
From what I understand, the style of playing was more or less a result of guitarist's Tony Iommi's accent with a steel cutter (I think) and cut off the tip of his finger. Was was able to play by putting a special cap on his finger. The album Paranoid was meant to be called War Pigs, which is the first track, but I think they were afraid of people getting mad at them or something.
Alice Cooper got his start (actually, I think its technically the 60s he got his start). Although he is technically sonisdered Heavy Metal, his music itself is not metal, its more rock. But he started the whole "freak out" performances, meant to freak out the audience. I wont go into details of some of what he did, might not be appropriate, but what I will say is his shows were filled with violence and gore.
Alice Cooper eventually appeared on this strange little show that is apparently pretty popular, although I cant say I ever saw it, The Muppet Show