Peter Lawrence Buck (born December 6, 1956) is an American musician and songwriter. He was a co-founder and the lead guitarist of the alternative rock band R.E.M.; he played the banjo and mandolin on several R.E.M. songs.

Throughout his career with R.E.M. (1980–2011), as well as during his subsequent solo career, Buck has been at various times a member of numerous side project groups. These groups included Arthur Buck (with Joseph Arthur), Hindu Love Gods, The Minus 5, Tuatara, The Baseball Project, Robyn Hitchcock and the Venus 3, Tired Pony, The No-Ones, and Filthy Friend