4. Venom, "Witching Hour" December 1981

Perhaps no NWOBHM act edged closer to pure thrash than Venom, a nasty little trio from Newcastle with a serious Satan fetish. Venom's music was faster, wilder and looser than their contemporaries, and their shock-rock affectations not only inspired thrash titans Slayer, but paved the way for death and black metal, too.

3. Black Flag, "Spray Paint" December 1981

In the late '70s, metalheads wanted nothing to do with the lo-fi sound and snotty nihilism of punk rock. It wasn't until speedy hardcore punk arrived in the early '80s, dripping with righteous aggression, that a few banging heads were turned.

Hardcore icons Black Flag were the most intense band of their era, and the buzzsaw ferocity of tracks like "Spray Paint" would soon find its way into mainstream metal. Somewhat ironically, Flag responded by growing out their hair and inserting slowed, Sabbath-style heaviness into their recordings, irritating virtually their entire fanbase in the process.

2. Overkill, "Unleash the Beast (Within)" 1981

While Metallica beat them to the punch in releasing an album, a case can be made that Overkill was writing and performing the first thrash originals months before Metallica began jamming on "Hit the Lights." "Unleash the Beast (Within)" is one of these early thrash tunes, a staple of the tape-trading circuit and an important milestone in the evolution of thrash metal.