No genre really comes to fruition in a vacuum. Regardless of how many people might like to think that their favorite artists were destined for greatness, everyone starts off copying some of their favorite acts that came before them. As the '60s went on though, things were taking a much darker turn on the rock charts.
Compared to the hippy idealism happening in the Woodstock crowd, there was a lot more caustic rock coming out of the woodwork, with gritty distortion and chaotic vocals becoming more and more prevalent on the charts. Rock was definitely starting to show its age, but there were a few bands looking to go even further. Being steeped in the blues and rock and roll traditions, these artists helped pave the way for what would become both hard rock and heavy metal later down the line, even informing some of the offshoots like grunge and punk in its wake. Granted, it's not like this kind of thing was planned by any means, with most of these artists just trying to find their identity in song.
Then again, genres like this aren't meant to arrive in one spot. It only happens when people follow behind you, and these bands have had more than their fair share of followers through the years.
10. The Stooges
By the time the Summer of Love rolled around, rock and roll could go in a lot of different places. As Chuck Berry and Jerry Lee Lewis were firmly in the rearview, the idea of going towards everything from folk to psychedelia to Eastern sounding music seemed wildly intriguing for your average musician. If you wanted to move the people though, you didn't need something flashy. You needed to get a little more primal.
Arriving like rats out of the sewer, the Stooges were out for blood when they first hit the rock scene, as Iggy Pop fashioned himself as rock's first true wild man. Compared to some of the more out-there talents of the time like Little Richard or even Jim Morrison, Iggy was one of the few artists that felt genuinely dangerous when he took to the stage, just as likely to get a rise out of the audience as he was to inflict personal harm on himself for a reaction.
Aside from the elaborate stage shows though, the rawness on display on records like Raw Power helped create a feeding ground for a more hectic form of rock, which we would later see in punk music and even the early sides of metal. As off-putting as something like the Stooges may seem on the surface, this is the kind of music that could tap into your animalistic side.