Theodor Walter Hirsbrunner (2 April 1931 – 6 November 2010) was a Swiss musicologist and violinist.
Born in Thun, Hirsbrunner attended an old-language grammar school. He then studied violin with Walter Kägi in Bern and René Benedetti in Paris. From 1956 he studied musical composition and music theory (twelve-tone technique) with Sándor Veress and Wladimir Vogel. In the 1960s he attended a conducting course with Pierre Boulez in Basel.
From 1956 to 1987 he taught music theory, work analysis, and more recently, historical musicology at the Hochschule der Künste Bern. From 1968 to 1973 he conducted research at the Bibliothèque nationale de France. From 1979 to 1983 he taught at Boulez' request at the IRCAM. He gave lectures in Europe (e.g. at the Lucerne Festival), Australia (Adelaide 1979), Japan (Tokyo 1989), Taiwan (Taipei 1999) and the USA (Berkeley 1977 and Los Angeles 1987) as well as on representatives of Neue Musik at European radio stations (BR, WDR, RSR, RIAS, NDR, SFB and DRS). In addition to numerous articles for specialist journals, encyclopaedias and newspapers, he wrote five monographs on musical personalities (Debussy, Stravinsky, Boulez, Messiaen and Ravel) and two volumes on the history of music.
He has received several awards, including the Chevalier des Arts et des Lettres.
Hirsbrunner died in Bern at the age of 79.