The album that started it all for these L.A. thrash progenitors--and helped usher in the speed and thrash metal movement of the '80s, and later the extreme metal underground of the '90s --still sounds fresh. In order to achieve their own special style, Slayer incorporated the faster, darker elements of Judas Priest and meshed it with the punk brutality of Motorhead, albeit without the bluesy roots of either of those British bands. While the artwork and lyrics are cartoonish on this self-produced, over-the-top debut, the band's energy and aggression shine, from the opening blitzkrieg of "Evil Has No Boundaries" to the final feedback squeals of the title track. Even as it is fueled by quasi-Satanic musings and raging testosterone, SHOW NO MERCY distinguishes itself from later Slayer releases by being slightly less thrashing. Indeed, it is more melodic than its successors, and the band balance things out with a number of mid-tempo passages that give the faster sections more power. SHOW NO MERCY is more black metal than thrash, and it proved a key influence on a wide range of bands within the metal underground over the following two decades.