James Roy Horner (August 14, 1953–June 22, 2015) was an American film composer and conductor. He worked on more than 160 film and television productions between 1978 and 2015.

He was known for the integration of choral and electronic elements alongside traditional orchestrations and for his use of motifs associated with Celtic music. Horner won two Academy Awards for his musical composition to James Cameron's Titanic (1997), which became the best-selling orchestral film soundtrack of all time. He also wrote the score for the highest-grossing film of all time, Cameron's Avatar (2009).