"Into the Void" on 1971's Master of Reality

There's not one guitarist who has had more influence on heavy metal than Black Sabbath's Tony Iommi. Iommi, now 65, is the godfather of heavy metal as we know it today, impacting several generations of bands from Judas Priest to Metallica to Soundgarden to Slipknot. And it's his killer riffs (his solos are stellar as well) that are Iommi's trademark as he's come up with some of the heaviest and intense chord progressions. While there are so many outstanding riffs within the Black Sabbath catalogue, here are five of Iommi's greatest riffs.

"Into the Void" at first might seem not to belong among the greatest Iommi riffs ever, but it's an example of a hypnotic verse riff that grinds like no other that had come before it. It's a perfect example of a riff that opened the door for other guitarist to emulate down the road and the riffs foreshadows the birth of doom and stoner metal. That doomy Iommi sound comes from his Gibson SG, old Laney amp and Rangemaster Treble Booster. Interestingly, Metallica's James Hetfield lists "Into the Void" as his all-time fave Sabbath track.

"Black Sabbath" from 1970's Black Sabbath

The epitome of the evil chord progression, the riff for "Black Sabbath" prominently uses the devil's interval with the flatted fifth of a power chord. The sound harkens to satanic connotations and musicians in times of old were burned at the stake for using it. It's the perfect signature riff for Sabbath to gain their false satanic label, which actually helped them garner more recognition. The riff haunts your brain and is a staple in modern metal.

"Snowblind" from 1972's Vol. IV

One of the best songs ever from Sabbath, the verse riff on "Snowblind" is an Iommi masterpiece with the first five power chords absolutely grinding along and, with the accompanying hard-hitting drum and bass accents, there is an added drama and tension, essentially driving home the hyped-up, altered reality of cocaine. Black Sabath thanks the "Coke Cola" on the album, and so do us fans if it inspired Iommi to create the "Snowblind" riff. As as aside, the band wanted to call the album Snowblind, but their record label wouldn't allow it.

Sabbath Bloody Sabbath from Sabbath Bloody Sabbath (1973)

One of Black Sabbath's signature songs, the track is propelled by Iommi's monstrous riff, which is another grinder that moves power chords down and then up again for that ear-pulverizing motion and power. The riff is even more amazing given the context that when Iommi wrote it, he was struggling to write anything. He thought the well had run dry, but then boom, he comes up with this timeless classic.

The Mob Rules from Mob Rules (1981)

This riff is one of those Iommi masterpieces that's like a runaway train of pure heaviness. The explosive riff combines some single notes and bending that gives a high-octane hint of blues to the sludge-fest. Sometimes it seems that the "Mob Rules" is a bit of a forgotten Sabbath album, but the title track features some of Iommi's finest work.

- Thanks to MMO for the valuable input.

Learn how a massive riff saved Black Sabbath in 1973