No Life 'Til Leather is Metallica's widely circulated demo tape. It received its name from the first line in the song "Hit the Lights". All the tracks are early recordings of songs that would later appear on the band's Kill 'Em All album. The track listing on Kill 'Em All is the same as that on the demo tape, save the addition of Cliff Burton's bass solo "(Anesthesia) Pulling Teeth", "Whiplash", "No Remorse" and "The Mechanix" (the latter of which was re-written by Metallica as "The Four Horsemen").

The demo has been re-released three times so far unofficially, first under the title of Metallica—Bay Area Thrashers, and was alleged to be a live bootleg recording of Metallica in the early days, however all 'live' sounds had been added from various sources including the Metallica video Cliff 'Em All. Soon this was discovered by Metallica and all copies were removed from stores. The second time it was re-released was under the title Metallica—In the Beginning... Live, which is exactly the same as Metallica—Bay Area Thrashers, but simply with a new title. The third release was called "Puppet Masters". It also contained the songs: "When Hell Freezes Over" (A demo version of a song that became "The Call Of Ktulu") and "Ride the Lightning". The band can be heard talking between the tracks, but it is unclear when this was added to the demo. This is the most well-known Metallica demo, showing the band's NWOBHM roots very clearly. The tracks are quite similar to the final versions on Kill 'Em All, apart from the modified lyrics for "The Mechanix" and "Jump in the Fire". "The Mechanix", a Mustaine written composition, turned into Metallica's own "The Four Horsemen". Mustaine recorded his own version of "The Mechanix" on Megadeth's debut album Killing Is My Business... And Business Is Good! The album, along with two other songs, can be found floating on many peer-to-peer networks under the moniker One Last Visit.