Robert "Bob" Ostertag (born April 19, 1957 in Albuquerque, New Mexico, United States) is an experimental sound artist, political activist and writer based in San Francisco. He has written three books, collaborated with a number of musicians, and has released twelve solo albums.
Fred Frith called Ostertag his "guru", and Robert Fripp once described him as "the only guy on synthesizer who interests me".