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 Friends, each of which have released at least one full-length studio album. Additionally, the experimental combo Slow Music have released an official live concert CD. Another side project group called Full Time Men released an EP while Buck was a member. As well, ad hoc "supergroups" Bingo Hand Job (Billy Bragg and R.E.M.), Musical Kings (Michelle Malone, Peter Buck, John Keane) and Nigel & The Crosses (Robyn Hitchcock, Peter Buck, Glenn Tilbrook and others) have each commercially released one track.

Richard M. Nixon, a band Buck founded in 2012 to support the release of his solo album with live gigs, has never issued an official recording. Richard M. Nixon consisted of Buck, Scott McCaughey and Bill Rieflin, the same three musicians who comprise The Venus 3.

Buck has a career as a record producer including releases by Uncle Tupelo, Vigilantes of Love, Dreams So Real, The Fleshtones, The Feelies, and The Jayhawks, as well as a session musician (The Replacements, Billy Bragg, Decemberists and Eels).

Peter Lawrence Buck was born on December 6, 1956, in Berkeley, California, to Peter and Violet Buck. After spending time in Los Angeles and San Francisco, the Buck family moved, via Roswell, Georgia, to Atlanta. After graduating with honors from Crestwood High School in 1975, Buck attended Emory University and joined Delta Tau Delta fraternity. He eventually dropped out of Emory. Buck moved to Athens, Georgia, and attended the University of Georgia as well. While in Athens, Buck worked at the Wuxtry Records store, where he met future bandmate Michael Stipe as well as R.E.M.'s future manager, Bertis Downs.

Buck's style of guitar playing is simple and yet distinctive. He makes wide use of open strings while chording to create chiming and memorable pop melodies. His sound, especially on mid-period R.E.M. albums that saw the band break through to international popularity, has been associated with Rickenbacker guitars, particularly a Jetglo (black) model 360. He has also used a wide variety of other instruments as the group continued to experiment and develop. On some more recent R.E.M. releases prior to Accelerate (2008), his guitar parts have been less prominent.

"When Peter plays guitar, there's a strong sense of fuck off that comes from his side of the stage. And you feel that he wants to be in a band because he likes what they do... but that's all," explained U2's lead singer Bono in 2003. "And it's almost like performing and having to deal with all of that is a bit of a compromise for him, so just fuck off. And I like that energy a little bit, and that gives them their aggression."

Buck has produced many bands, including Uncle Tupelo, Dreams So Real, Drivin N Cryin, The Fleshtones, Charlie Pickett, and The Feelies. Buck also has made contributions on many other musicians' albums, including The Replacements, Billy Bragg, The Decemberists, Robyn Hitchcock, and several Eels albums.

Peter, Mike Mills, Bill Berry and Warren Zevon recorded an album under the band name Hindu Love Gods, while the R.E.M. bandmates and Zevon were recording tracks for Zevon's 1987 album Sentimental Hygiene. Hindu Love Gods is one of many names the members of R.E.M. have used performing around the Athens area. Buck also continued to play live locally with the Normaltown Flyers, performing country and rock standards in local bars.