Black Sabbath

If it must be heavy, then let it be heavy. Let there be granite-like and malign riffs, feedback-heavy bass, hysterical drums, and hallucinatory vocals. To hell with melodic excesses and unnecessary virtuosity. To hell with intrusive keyboards and organs. The leading instrument in this genre must be the guitar. That's why I find things like Space Truckin' by Deep Purple inconceivable. That's why the true flagbearers of the genre, the number 1s, are Black Sabbath, the first Black Sabbath.