Phil Demmel is an American musician who played lead guitar in the heavy metal band Machine Head between 2002 and 2018, making him their longest running member in that position. He has also performed with other artists such as Vio-lence, Torque, Metal Allegiance, BPMD, Kerry King and Category 7, and briefly played with Slayer, Nonpoint, Overkill, Lamb of God and Testament as a fill-in guitarist.

Machine Head is an American heavy metal band from Oakland, California. The band was formed in 1991 by vocalist/rhythm guitarist Robb Flynn, who remains the only original member of the band. Machine Head's aggressive musicianship made it one of the pioneering bands in the new wave of American heavy metal. Its current lineup comprises Flynn, bassist Jared MacEachern and drummer Matt Alston. Bassist Adam Duce, lead guitarists Logan Mader, Ahrue Luster and Phil Demmel, and drummers Tony Costanza, Chris Kontos and Dave McClain are former members of the band; Mader and Kontos toured with the band in 2019 and 2020 as part of the 25th anniversary tour for its first album, Burn My Eyes (1994).