John Anthony Frusciante (born March 5, 1970) is an American guitarist, singer, songwriter and record producer. He is best known as the guitarist of the alternative rock band Red Hot Chili Peppers, with whom he has recorded five studio albums. Frusciante also maintains an active solo career, having released nine albums under his own name, as well as two collaborations with Josh Klinghoffer and Joe Lally, under the name Ataxia. His solo recordings incorporate a variety of elements ranging from experimental rock and ambient music to New Wave and electronica. Drawing influence from guitarists of various genres, Frusciante emphasizes melody and emotion in his guitar playing, and favors vintage guitars and analog recording techniques.

Frusciante joined the Red Hot Chili Peppers at the age of eighteen, first appearing on the band’s 1989 album Mother’s Milk. The group’s follow-up album, Blood Sugar Sex Magik, was a breakthrough success. However, he was overwhelmed by the band’s newfound popularity and as a result quit in 1992. He became a recluse and entered a long period of heroin addiction, during which he released his first recordings: Niandra Lades and Usually Just a T-Shirt and Smile from the Streets You Hold. In 1998, Frusciante successfully completed drug rehabilitation and rejoined the Chili Peppers for their 1999 album Californication. Since then he has continued to record with the band and has received critical recognition for his guitar playing, ranking eighteenth on Rolling Stone’s list of "The 100 Greatest Guitarists of All Time" in 2003.

Frusciante was born in Queens, New York on March 5, 1970. His father, John Sr., was a Juilliard-trained pianist, and his mother Gail was a promising vocalist who gave up her career to be a stay-at-home mother.Frusciante’s family relocated to Tucson, Arizona, and then Florida, where his father still serves as a Broward County judge. His parents separated, and he and his mother subsequently moved to Santa Monica, California.

Frusciante’s musical style has evolved significantly throughout his years of playing. Although he has received moderate recognition for his guitar work in the past, it was not until Stadium Arcadium that music critics and guitarists alike began to fully recognize his work. Frusciante attributes this to his shift in focus, stating that he chose an approach based on rhythmic patterns that were inspired by the complexity of material Jimi Hendrix and Eddie Van Halen produced. On preceding records, however, he centered much of his output around the influence of various underground punk and New Wave musicians. In general, his sound is also defined by an affinity for vintage guitars. All the guitars that he owns, records, and tours with were crafted prior to 1970. Frusciante’s most prized instrument is a 1957 Gretsch White Falcon, which he used twice per show during the By the Way tour. He has since removed the White Falcon from his repertoire, feeling there was "no room for it". Virtually all of Frusciante’s acoustic work is played with a vintage 1950s Martin 0-15.

Frusciante uses a variety of vocal styles on his solo albums, ranging from the distressed screeches heard on Niandra Lades and Usually Just a T-Shirt and Smile from the Streets You Hold, to more conventional styles on subsequent records. With the Chili Peppers, Frusciante provides backing vocals in a falsetto tenor, a style he established on Blood Sugar Sex Magik. He thoroughly enjoys his role in the Chili Peppers as backup singer, and feels that backing vocals are a "real art form". Despite his commitment to the Chili Peppers, he feels very strongly that his solo material and his contributions to the band should remain separate. When he returned to the Chili Peppers in 1999, Kiedis wanted the band to record "Living in Hell", a song Frusciante had written several years prior. Frusciante rejected the request, feeling that the creative freedom he needs for his solo projects could conflict with his role in the band.