Surfing With the Alien, by Joe Satriani
In 1987 Joe Satriani did something almost completely unthinkable: put out an entirely instrumental guitar oriented album that made it high into the charts. It's not surprising Surfing With the Alien became so popular though because so many of the songs are incredibly memorable despite the fact there are no vocals. The songs range from ripping and running to slow and melodic. Satriani really did bring the art of technical shred to the public in a way they could really understand it.
Van Halen, by Van Halen
How could I NOT have this album in my list? Without Van Halen rock and metal as we know it today would simply not exist. Eruption alone was enough to inspire multiple generations of guitar players trying to copy Eddie Van Halen by learning how to finger tap on their fret boards and create all kinds of wicked melodies; some better than others of course. Aside from that, the album pretty much laid the foundation for what would in a couple years be the hair metal movement, which say what you will about it - some of those bands could REALLY play.
Led Zeppelin, by Led Zeppelin
Before Led Zeppelin there really wasn't such a thing as hard rock. Their debut album was a real game changer starting from track 1 all the way to the finish. By taking the blues and adding a loud gritty edge to it, upping the tempo in some areas, and then in some moments completely blasting things into outer space Led Zeppelin laid the foundation for countless bands to come. Nothing had ever sounded that big and monstrous before. Everything had been all psychedelic or folksy up to that point. Thanks to the vision of Jimmy Page Led Zeppelin took rock n' roll and for the first time really gave it some balls.
Are You Experienced, by The Jimi Hendrix Experience
Naturally Hendrix was going to come into this list sooner or later. The man practically invented the art of the guitar solo as well as funk music. Plus, before Led Zeppelin came along he was the closest thing to hard rock that existed, taking the blues and going in an exploratory direction with it. Hendrix's debut album Are You Experienced is absolutely dripping with the fuzz, fire, and acid trip fueled musical adventure that he would become known for. This album alone due to Hendrix's imaginative song writing and playing technique really does show why many consider him to be the greatest guitar player to ever live.
The Complete Recordings, by Robert Johnson
Without Robert Johnson we more than likely would not have rock n' roll or any of the great guitar players that we know and love today. His simplistic warm delta blues style was pretty much the blueprint for virtually everyone who came after him. In the late 1920's/early 1930's he wrote and soulfully performed countless blues standards like Sweet Home Chicago, Crossroads, From Four Till Late, and more. I would honestly venture to say that this guy is the father of the blues and popular music as we know it.