Peter "Spike" Cassidy (born October 7, 1961) is an American guitarist. He is a member of crossover thrash band DRI (Dirty Rotten Imbeciles).
Cassidy was born in Queens, New York and grew up in Sound Beach, New York.
Cassidy, who played guitar, helped form DRI in 1982 when he was 21 years old, along with his friend Kurt Brecht, Kurt's brother Eric Brecht on drums, and Dennis Johnson on bass. After releasing their first album in 1983, D.R.I. experienced its first lineup change, with Eric and Dennis Johnson leaving the band in 1984. Since then, D.R.I. would go through many lineup changes, although Cassidy has remained constant as the guitarist alongside vocalist Kurt Brecht who also has been an all time permanent member.
With the release of the highly regarded but commercially unsuccessful 1985 album Dealing with It!, D.R.I. abandoned the hardcore punk style of the their first album for a crossover thrash style, which would continue on their next four albums, Crossover (1987), 4 of a Kind (1988), their breakthrough Thrash Zone (1989), and Definition (1992). After weak sales of their last studio album date, Full Speed Ahead (1995), D.R.I. had decided they would no longer record any new music, although the band's wiki page states "TBD" for their next album's release date. D.R.I. has continued touring almost constantly for years.