Killbox 13 is the 12th studio album by thrash metal band Overkill in 2003. The name stems from the fact that the band considers this to be their thirteenth release because they include the Overkill EP as their first, or that they had released the covers album Coverkill, which would have been their eleventh studio album. "Well, it is the thirteenth, but it's only really the thirteenth for people who followed the band. There was an EP called Overkill back in '84...", said Bobby Ellsworth.
Killbox 13 received much critical acclaim because some of the songs marked a return to the raw unpolished thrash style exhibited on the first album Feel The Fire, which Overkill had gradually moved away from afterwards.