6. Black Sabbath - Paranoid
https://www.youtube.com/watch?v=Nxgtk_3qwXw Not content with changing the world once over with their self-titled debut album (also a totally worthy candidate for inclusion in this album's slot), Sabbath thought they'd best remind everyone how to write a perfect mood-setting intro while they're on. With recent tours showing that the songwriting held within these tracks hasn't aged a day, as soon as Ozzy blares out the iconic "Generals gathered in their masses...." line in between the immortal Tony Iommi's dual-chord-stabs with Bill Ward's foot-cymbals ticking away like some demonic time-bomb in the background on War Pigs, it's metal songwriting 101 and then some. That's not even to mention the time-changes and liberal fiddling-with of tones, scales and lyrics throughout the album that makes it so easy to return to and gain something new from. Fairies Wear Boots is one of the most lyrically-relatable tracks Sabbath would ever put out, starting as some description of nightmarish elements and devolving into Ozzy's trip to the doctors - the combination of the two ended up together just for the sake of it. And that's not even mentioning the mainstream chart-slaying title track that so many associate with the band or the only other riff to sit up there with Smoke on the Water and Sweet Child O' Mine; the more metal-than-its-superheroic-namesake; Iron Man. It's impossible to get sick of: Iron Man. The riff is so solid it could rebuild a fallen civilisation just as easily as it unites hundreds of thousands of fans the world over under the brotherhood-banner of metal every time those chords come thundering in.