Killing Joke are an English post-punk group which formed in October 1978 in Notting Hill, London, England. (Several sources state that they formed in early 1979.) Founding members Jaz Coleman (vocals, keyboards) and Geordie Walker (guitars) have been the only constant members. A key influence on industrial rock, their early music was described by critics Stephen Thomas Erlewine and John Dougan as well as industrial metal and "quasi-metal ... dancing to a tune of doom and gloom," which gradually evolved over the years, incorporating elements of electronic music, synth-pop, gothic rock, and alternative rock, though always emphasizing Coleman's "savagely strident vocals." Finding modest commercial success, Killing Joke have influenced many later bands, such as Nirvana, Ministry, Amen, Lamb of God, Nine Inch Nails, Napalm Death, Amebix, Big Black, Godflesh, Tool, Prong, Metallica, Primus, Jane's Addiction, Soundgarden, Foo Fighters, Faith No More, Blacklist, Shihad and Korn, all of whom have at some point cited some debt of gratitude to Killing Joke.