Tracing the real origins of the hard rock genre can get a bit tricky. While many would focus on a band like the Kinks for reinventing the idea of heavy with You Really Got Me, others would point to acts like Led Zeppelin or Black Sabbath for recontexualizing how we look at the harsher forms of rock. If there was any band deserving of the title of first hard rock act though, Cream makes for an interesting case.
Formed once Eric Clapton split ties with the Yardbirds, Cream were among one of the first true supergroups ever conceived, with Ginger Baker bringing his trademark percussion thunder after spending time playing in John Mayall's Bluesbreakers. Along with the incredible musicianship at work, Cream had a great knack of playing off one another, with Clapton's soft spoken vocals playing off of the soulful wail of Jack Bruce often within the span of a single song.
The real star of the show came when they took the trademark blues numbers and slowed them down, bringing a slow and dripping swagger that sounded like a blues juke joint if it were bellowing from the edge of the underworld. The Rolling Stones might have injected some menace into rock and roll, but tracks like Sunshine of Your Love mark the moment that blues became hard rock.