David Bowie. He has also manipulated sound in many musical outfits including Nine Inch Nails, Blast Conservatory, Cleopatra System and Full Court Press (a band he was in), as well as working in Naut Humon's Sound Traffic Control. Keith Hillebrandt has also released four solo albums and an EP.
On David Bowie's I'm Afraid Of Americans, Hillebrandt is listed as a full member of NIN along with Dave Ogilvie, Danny Lohner and Charlie Clouser. He was evidently planned to be part of a multiple-keyboardist setup for the live band that Trent Reznor originally put together for the Fragility tour, but The Fragile took a different route sonically and this idea was scrapped, although he did replace Charlie Clouser during the CRC Sessions.
Body Of Work
Nine Inch Nails