Adrian Belew (born Robert Steven Belew, December 15, 1949) is an American musician, songwriter and record producer. A multi-instrumentalist primarily known as a guitarist and singer, Belew is noted for his unusual, impressionistic approach to guitar playing (which frequently involves sounds more akin to animals and machines than to standard instrumental tones). He is perhaps best known for his work as a member of the progressive rock group King Crimson which he fronted, but did not lead, from 1981 to 2009 (for the 2013 reformation of King Crimson, bandleader Robert Fripp replaced him with Jakko Jakszyk).

Widely recognized as an "incredibly versatile player", Belew has released nearly twenty solo albums for Island Records and Atlantic Records which blend Beatles-inspired pop-rock with more experimental fare. His 2005 single "Beat Box Guitar" was nominated for a Grammy in the Best Rock Instrumental Performance category. In addition to being a member of King Crimson, he is also in the more straightforward pop band The Bears and fronted his own band, "GaGa", in the late 1970s and early 1980s. He has worked extensively as a session and touring musician, most famously with Talking Heads, David Bowie, Frank Zappa, and Nine Inch Nails. His latest project is a set of iOS mobile app platforms called respectively FLUX by belew and FLUX:FX. FLUX by belew contains over 300 audio tracks and pieces of artwork that Adrian describes as "never playing the same twice". FLUX:FX is a realtime audio manipulation app for the iPad that he has designed to, in his own words: "let me make sounds that i can't get with any other gear.".

Belew has also worked in instrument design, collaborating with Parker Guitars to help design his own Parker Fly signature guitar. This guitar is noticeably different from the standard design, containing advanced electronics such as a sustainer pickup and a Line 6 Variax guitar modelling system. It is also MIDI-capable, allowing it to be used with any synthesizer with MIDI connectivity.