Warren Justin DeMartini is an American musician best known as the lead guitarist for glam metal band Ratt, which achieved international stardom in the 1980s.

Ratt is an American heavy metal band that had significant commercial success in the 1980s, with their albums having been certified as gold, platinum, and multi-platinum by the RIAA. The group is perhaps best known for hit singles such as "Round and Round" and "Lay It Down", tracks that ranked on Billboard's top 40 at No. 12 and No. 40, respectively, as well as other songs such as "Wanted Man", "You're in Love" and "Dance". Along with groups such as friendly rivals Mötley Crüe, Ratt has been recognized as instrumental in the formation of the early 1980s Los Angeles glam metal scene, also known as "hair metal" or "pop metal".