Horner was an concert hall composer before moving into films. His first soundtrack of genre interest was Battle Beyond the Stars in 1981, but he hit the big time when he was picked to score Star Trek II: The Wrath of Khan the following year. His score was highly praised for the way it backed both the action and character moments perfectly. He also scored Star Trek III: The Search for Spock.
This moved Horner into the big leagues and he scored many of the most well-known movies of the 1980s and 1990s, including 48 Hours, Krull, Cocoon (and its sequel), Commando, An American Tail, *batteries not included, Willow, Red Heat, The Land Before Time, Field of Dreams, Honey, I Shrunk the Kids, Glory, The Rocketeer, Patriot Games, The Pelican Brief, Clear and Present Danger, Legends of the Fall, Braveheart, Apollo 13, Jumanji, Deep Impact, The Mask of Zorro and The Bicentennial Man.
In 1986 Horner began a highly fruitful collaboration with the director James Cameron. He produced the acclaimed soundtrack to Aliens before working with the director on Titanic. Horner won his only two Academy Awards for the film, both for the score and for the song "My Heart Will Go On" (sung by Celine Dion). In 2009 they reunited so Horner could produce the score for Avatar. Both Cameron and Horner had indicated that Horner would return to score the Avatar sequel trilogy, but it's unknown if Horner had already begun working on that project at the time of his passing.
James Horner was acclaimed as one of the "Three Js" of film scoring in the latter part of the 20th Century, alongside the late Jerry Goldsmith and the still-going-strong John Williams. He soundtracked many of favourite movies of all time and he will be missed.