Judas Priest - Stained Class
An album that also shaped my understanding of heavy metal - I actually purchased it when it came out. I had seen pictures of Judas Priest, but I hadn't actually heard any music. I'd read they were a fantastic band but I didn't really know what I was in for. Then I put on Stained Class and what I heard was a completely unknown brand of surgically precise modern metal - there was no other band that had this absolute metal style. That was really the invention of metal, even though of course Black Sabbath were before, but Priest really reinvented themselves with Stained Classs, and they also reinvented the entire genre of heavy rock - this album was a true revelation. I remember very distinctly when I listened to it in 1978 I actually had to get used to it first. It was almost too modern for me at that age.

As fantastic as the early albums are as well, on Stained Class they had this inexplicable groove - they had a really distinctive style of writing songs, and they were so precise. They kept that style for a few albums, and it's incredibly unfortunate that they later lost that style and became much more regular metal. I lament that always. I'm still a fan, of course - how can you not be a fan? - but if you listen to the last two or so Priest albums they're much more normal metal as opposed to Killing Machine, British Steel, Stained Class, when they had a style that only they had. They succumbed to the pressure to become more commercial - that wasn't easy to see, as a fan of their earlier stuff. I absolutely wish they could write an album again with that unique groove that's missing from so many other bands in metal.