Here's an interesting factoid for Metallica and Soundgarden fans. In a recent interview withn 98.5 The Sports Hub Toucher & Rich, Metallica guitarist Kirk Hammett reveals that Soundgarden's sophmore album, Louder Than Love, is what inspired the riff on "Enter Sandman."
"But how?" you might ask? Well, let's let Kirk tell the story.
"It was about two or three o'clock in the morning. I had just been listening to Louder Than Love, the [second] Soundgarden album," Hammett recalls. "It was when Soundgarden [was] still somewhat underground and [was] on an independent label. I just love that album; it's a great Soundgarden album. And I heard that album, I was inspired, I picked up my guitar, and out came that riff."
Hammett clarified that he wasn't exactly trying to rip off a Soundgarden riff, just that listening to the album gave him the motivation to write what become the most iconic riff in Metallica's catalog:
 "It doesn't sound like a Soundgarden riff," said the guitarist. "It doesn't sound like a Soundgarden song; I was inspired by Soundgarden for sure, without a doubt – but I moved on to create something completely different."
Well, it's a good thing Kirk was listening to Soundgarden and not like "Rico Suave" or a Mariah Carey tune or "Enter Sandman" would have a whole different feel to it.