Ian Underwood (New York, NY, 22 May 1939) is an American multi-instrumentalist musician. He was a member of the Mothers of Invention between 1968 and 1973. Underwood is additionally notable for having been married to Ruth Komanoff (aka Ruth Underwood) between May 1969 and 1986.
Ian Underwood graduated from Yale with a BA in composition in 1961 and completed a Masters degree in compostion at UC Berkeley in 1966. He was a concert pianist specializing in Wolfgang Amadeus Mozart.
Ian's "story" of meeting and joining Zappa is memorably chronicled in the track Ian Underwood Whips It Out on the Uncle Meat release. Here he introduces himself as the "straight member of the group". In the sleeve of Burnt Weeny Sandwich he can be seen biting into a baby doll's leg and exclaim: "God, this IS a tasty sucker!".
He performed piano, organ, keyboards, woodwinds, guitar, and/or vocals on the albums We're Only In It For The Money (1968), Cruising With Ruben & The Jets (1968), Uncle Meat (1969), Hot Rats (1969), Burnt Weeny Sandwich (1970), Weasels Ripped My Flesh (1970), Chunga's Revenge (1970), Fillmore East, June 1971 (1971), Frank Zappa's 200 Motels (1971), Just Another Band From L.A. (1972), Over-Nite Sensation (1973), Apostrophe (') (1974) and Zoot Allures.
He can additionally be heard on later compilation albums: You Can't Do That On Stage Anymore Vol. 1, You Can't Do That On Stage Anymore Vol. 3, You Can't Do That On Stage Anymore Vol. 4, You Can't Do That On Stage Anymore Vol. 5, You Can't Do That On Stage Anymore Vol. 6, Playground Psychotics, Ahead Of Their Time, The Lost Episodes, Mystery Disc, QuAUDIOPHILIAc, Joe's Domage, Wazoo and the Beat The Boots' series The Ark (BTB), Freaks & Motherfuckers (BTB), 'Tis The Season To Be Jelly, Piquantique (BTB), Disconnected Synapses (BTB), Tengo Na Minchia Tanta (BTB), Electric Aunt Jemima (BTB), At The Circus (BTB), Swiss Cheese/Fire! (BTB) and Our Man In Nirvana (BTB).
Apart from his work with Zappa he has contributed to many recordings by artists ranging from Gabor Szabo to Barbra Streisand. He also performed on Sandy Hurvitz's Sandy's Album Is Here At Least (1969), Jeff Simmons' Lucille Has Messed My Mind Up (1969), Captain Beefheart's Trout Mask Replica (1969), Alice Cooper's Pretties for You (1969), Jean-Luc Ponty's King Kong: Jean-Luc Ponty Plays the Music of Frank Zappa (1970), Flo & Eddie's Illegal, Immoral and Fattening (1975) and Moving Targets (1976), as well as Gabor Szabo's Macho (1975), Chunky, Novi & Ernie's eponymous 1977 debut album.
Since the 1980s and 1990s he has played synthesizer on many film soundtracks including Blade Runner (1981), Krull (1983), Aliens (1986), Honey, I Shrunk the Kids (1989), Braveheart (1995) and Titanic (1997). He notably performed synthezier on U.S.A. for Africa's single We Are The World.
Ian Underwood was also mentioned and thanked in the liner notes of The MOFO Project/Object (2006) album.  He is interviewed in the documentaries Frank Zappa - The Freak-Out List (2010) and Frank Scheffer's Frank Zappa: The Present-Day Composer Refuses To Die (2000), Frank Zappa Phase II: The Big Note (2002) and Frank Zappa: Pioneer Of Future Music, parts 1 & 2 (2007). He wrote the liner notes to the album Meat Light - The Uncle Meat Project/Object Audio Documentary (2016). Underwood contributed an essay to The Hot Rats Book (2019).