You could at this point probably make an argument for Black Sabbath being the universe's most influential rock band. It's a hot take, I know, but hear me out: just take a glance at the legions, the seasons of hard rockin', psych riffin', weed applaudin' bands the world is enduring as a direct result of Ozzy and co's old ways. Sabbath culture is alive and well in the metal of today; without them there'd be no Sleep, for crying out loud, who characterised their old album art with the Sabbath typeface.
Ozzy Osbourne is the headline feature for Sabbath, though in reality he was enlisted by founding members Tonny Iommi and Bill Ward, the band growing their first crop of cruelty, the eponymous Black Sabbath, with the fabulously named Geezer Butler on bass. It wasn't a classic, but what came after was metal's greatest hot streak: the iconic riff-fest of Paranoid into the slow, skeletal Master of Reality, into the experimental Vol. 4 through to piece de resistance Sabbath Bloody Sabbath. This frightening quartet of records led the way for metal bands who wanted to do more with less, setting up slow ascensions for solo treatises and the more traditional hallmarks of heaviness.
Without Sabbath we'd probably have way less thinking out of the box in modern metal; they opened up a world where this kind of music could exist with restraint and ecstasy.