Usurper is an American black, death and thrash metal band from Chicago, Illinois, formed in 1992 by members of The Dead Youth as a side project. The founding lineup included guitarist Rick S. Scythe, vocalist Dave Piekarz and drummer Joe Schaeffer. The band took its name from a song by the Swiss group Celtic Frost. Usurper released its debut album Diabolosis in 1995 through the Norwegian label Head Not Found, featuring bassist Jon Necromancer.