Robert Steven "Adrian" Belew (born December 23, 1949) is an American musician, singer, songwriter, and record producer. A multi-instrumentalist primarily known as a guitarist and singer, he is noted for his unusual approach to the instrument, his playing cited as fluid, expressive, and often resembling "animal noises or mechanical rumblings".

Widely recognized as an "incredibly versatile [guitar] player", Belew is perhaps best known for his tenure as guitarist and frontman in the progressive rock group King Crimson between 1981 and 2009. He has also released nearly twenty solo albums for Island Records and Atlantic Records in various styles. In addition, Belew has been a member of the intermittently active band the Bears, and fronted GaGa in the late 1970s and early 1980s.

Belew has also worked extensively as a session, guest, and touring musician, including periods with Frank Zappa, David Bowie, Talking Heads, Laurie Anderson, and Nine Inch Nails, as well as contributing to hit singles by Paul Simon, Tom Tom Club, and others. His 1989 solo single "Oh Daddy" was a top ten hit in the United States, and his 2005 single "Beat Box Guitar" was nominated for a Grammy Award for Best Rock Instrumental Performance. Belew has also worked in instrument design and multimedia, collaborating with Parker Guitars to help design his Parker Fly signature guitar, and designing two iOS mobile apps.

Robert Steven Belew was born into a middle-class family in Covington, Kentucky, on December 23, 1949. Initially known to friends and classmates as "Steve", he played drums in his adolescence, playing with the Ludlow High School marching band and later with the high school cover band the Denems. Inspired by Jimi Hendrix, he took up guitar while bedridden with mononucleosis. At the age of 17, he was further inspired after witnessing a live performance by Lonnie Mack, who later became a close friend.

Not inclined to formal music study, Belew primarily taught himself guitar by listening to records. He was not aware of the studio sound manipulation used to create particular guitar lines, and so found ways of replicating them himself manually using unusual playing techniques and effects pedals. While maturing as a player and mastering various playing styles, Belew became increasingly preoccupied with ways to avoid "sounding like everybody else". He eventually found his own sound and style by learning how to make his guitar mimic sound effects such as car horns, animal noises, or industrial sounds.

In the mid-1970s, Belew began using the first name "Adrian" and moved to Nashville to pursue a full-time career as a professional musician. By 1977, he was playing with the regionally popular cover band Sweetheart, but wondered whether he had missed his chance to make a living with original music.

In 1977, while playing with Sweetheart at Fanny's Bar in Nashville, Belew was discovered by Frank Zappa, who had been tipped off regarding the band's talents by his chauffeur. Zappa approached Belew and discussed auditioning him for an upcoming tour, although Belew did not receive an official invitation to audition for the better part of a year. During this time Sweetheart split up. Once the formal invitation came, Belew flew out to Los Angeles and found himself auditioning alongside more formally trained musicians. Believing that he had performed poorly, Belew persuaded Zappa to give him a second audition, a more intimate experience which took place in Zappa's living room. Zappa was impressed enough to hire Belew as a guitarist and vocalist for a year.

Belew toured with Zappa in 1977 and 1978, and appeared on Zappa's 1979 album Sheik Yerbouti and concert film Baby Snakes. While with Zappa, Belew was mostly credited as a rhythm guitarist, although he also played lead, melody, or noise lines, and sang lead vocals on the songs "Jones Crusher" and "City of Tiny Lites". According to Belew, "Frank either played or sang, never both at the same time, so ultimately my role became covering his parts. When he sang I played his guitar part. When he played I sang his vocal part." He also took on the role of band clown, performing impressions (such as the Bob Dylan impersonation on the song "Flakes"), wearing unusual clothing, and performing visual stunts. ("Need someone to wear a flashing helmet and bounce around like a robot? How about Adrian? Need someone to wear a dress onstage? There's always Adrian.")