William Boucaya (1922, † 1985) was a French jazz musician (baritone saxophone, also alto saxophone, bass clarinet).

Boucaya worked in the post-war Paris scene of modern jazz; he played from the mid-1940s with Hubert Rostaing (Chelsea Bridge), 1950 in its sextet. During this time, he also worked with Roy Eldridge, Claude Bolling, Bill Coleman, Bill Tamper, André Hodeir, Henri Renaud’s All-Stars, Gigi Gryce, Jack Dieval, Christian Chevallier, André Persiany, Dave Pochonet, Guy Lafitte, Bobby Jaspar as well as with the American jazz stars Lionel Hampton, Chet Baker, Clifford Brown and Lucky Thompson. In the second half of the decade, he also worked on recordings by Benny Vasseur, Armand Migiani, Martial Solal, Sacha Distel, Michel Legrand, Eddie Barclay, Sarah Vaughan, Alain Goraguer (soundtrack of Les Loups Dans La Bergerie, 1959). At the beginning of the 60s he played with Martial Solal (soundtrack of Si Le Vent Te Fait Peur) and in the studio band, which recorded the soundtrack to Paris Blues (with Louis Armstrong). In the early 1960s, he worked again with Rostaing and Lafitte, also with the singer Tony Milton. In 1963 he was a member of the big band of Jef Gilson. In the field of jazz he was involved in 76 recording sessions between 1947 and 1969, most recently with Maxim Saury and The Three Dimensional Band.

His playing on the baritone saxophone was influenced by Gerry Mulligan.