It's very well known that Black Sabbath started it all with their debut. But which bands actually followed that path?

Does Nazareth count? Not really heavy metal buy today's standards', but I would imagine they would have been 'heavy' during the mid-70's.

assuming this is a genuine query, it's been asked too many times before, here and elsewhere. you can google "proto metal" and start from there. "sad wings of destiny" is 1976, if you want an easy pointer...

Deep Purple, Nazareth, Ted Nugent, Judas Priest, Rainbow, Motorhead, Uriah Heep, Saxon, and Scorpions would be "70s Metal Bands." ...oh yeah and BUDGIE!!!!!!!!! Tons of 70s stuff was borderline Hard Rock or was very very influenced by prog. Motorhead was metal-punk hybrid, UFO / Scorpions was metal. Rainbow ventured close to pop and prog but it still considered metal.

Certain Deep Purple songs were metal, with Highway Star pretty much being the first speed metal songs and paved the way for Motorhead.

For Judas Priest, Rocka Rolla was not metal but Sad Wings most certainly was.

Shit, even Black Diamond by Kiss is a straight up heavy metal song