Robert "Bob" Ostertag (born April 19, 1957) is a musician, writer, and political activist based in San Francisco. He has published seven books, one feature film, a DVD, twenty-six albums, and collaborated with numerous musicians. Musically, he is known for his politically charged compositions created from found sound (Sooner or Later, All the Rage), his work with synthesizers over 45 years (from Bob Ostertag Plays the Serge 1978-1983 to Wish You Were Here in 2016), and his many collaborations (Anthony Braxton, John Zorn, Fred Frith, Justin Vivian Bond, Shelly Hirsch, and Roscoe Mitchell to name just a few). In his writing, films, and podcasts, he has addressed LGBT issues, poverty, climate change, and technology, from a militant yet non-ideological perspective. On March 25, 2006, Ostertag made all of his recordings to which he owns the rights available as digital downloads under a Creative Commons Attribution-NonCommercial 2.5 license.