Antonius Wilhelmus Adrianus de Leeuw (born Rotterdam, 16 November 1926; died Paris, 31 May 1996) was a Dutch composer. He occasionally experimented with microtonality.
Taught by Henk Badings, Olivier Messiaen and others, and in his youth influenced by Béla Bartók, de Leeuw was a teacher at the University of Amsterdam and later professor of composition and electronic music at the Sweelinck Conservatory in Amsterdam from 1959 to 1986, at which institute he served as director from 1971–73. For his notable students, See: List of music students by teacher: K to M#Ton de Leeuw.
"When I was quite young I once accidentally tuned in on a radio broadcast from an Arabian station. I was thunderstruck: I became deeply aware that there were other people living on this earth, living in thoroughly different conditions, having other thoughts and feelings" (Ton de Leeuw, 1978).
He studied ethnomusicology with Jaap Kunst between 1950 and 1954 and the encounter with the Dagar brothers and Drupad on his first visit to India in 1961 deepened a lifelong interest in "transculturation". Since then he has travelled throughout the world: Japan, Indonesia, Australia, the Philippines, Persia, the Sovjet Union, Hungary, Bulgaria and Finland, where he hold workshops and lectures on the East-West relationship in music. In the seventies de Leeuw and André Jurres initiated the renowned Music-Cultural gatherings Musicultura at Queeckhoven House in Breukelen, the Netherlands. See: The World of Music Vol. 20, No. 2, Musicultura: Three Orient-Occident Encounters organized by the Eduard van Beinum Foundation—Final Report (1978), pp. 10–14. This manifested itself in his work for Western instruments by the occasional use of microtonality, as in his String Quartet No. 2 (1964), as well as in compositional plans; Gending (1975) for Javanese gamelan is a rare foray into writing for non-western instruments. In 1956 Ton de Leeuw was awarded the Prix Italia for his radiophonic oratorio Job.