"My job," James Horner once told an interviewer. "Is to make sure at every turn of the film it's something the audience can feel with their heart." (Source)
That means he likes his music big and bold, and you can see that on full display in Star Trek II. He comes from the same tradition as John Williams, with a lot of heavy brass instruments and a pounding, operatic quality to it all. That's in keeping with a space opera, of course, which is probably a big reason why he got the job.
Horner got started at the Royal College of Music in London, but came out to Los Angeles to teach music theory at UCLA. He started composing short bits for student films at the nearby American Film Institute…and then moved on to working for B-movie king Roger Corman. His first official score was for Corman's space-age Seven Samurai remake Battle Beyond the Stars, which readily set him up for the kind of operatic grandeur that Star Trek II required.
Still, he was in the lower echelon of things, and had Star Trek II gotten a little more love from the budget department, he might never have gotten his shot at the big leagues. Jerry Goldsmith, who composed the score for Star Trek: The Motion Picture and ranked among a tiny handful of the greatest film composers of all time, was way out of their price range.
So they went with Horner, giving the kid a shot to see what he could do.
Launched Into the Stratosphere
And he nailed it. Horner used a lot of operatic brass and larger-than-life themes, loosely following the trend set by Goldsmith for the first Star Trek movie, and John Williams for the Star Wars films. Yet he found his own rhythm and unique voice for the themes here: Star Trek to be sure, but definitely his take on Star Trek.
His ideas reflected Williams' ethos of telling the story through the music, underlining the emotional themes in a big, bold way that no one could possibly miss. Khan's theme is menacing and larger than life. The Enterprise gang gets something more along the lines of plucky underdog (and string intensive). Spock's theme is meditational and a little alien. At every turn, Horner informs us of the emotions on screen, augmenting the drama rather than competing with it.
And with it, he was off to the races, composing a total of 157 scores, including the notable 48 Hrs., Aliens, Willow, Glory and Apollo 13. He also landed the score to Titanic, which became the highest grossing film of all time for a while and netted him a pair of Oscars (one for the proper score and one for "My Heart Will Go On," which will endure forever in the hearts of Celine Dion lovers and dentists' offices everywhere). (Source)
He landed himself eight other Oscar nominations along the way, and eventually became one of Hollywood's go-to guys for snazzy film music. It's safe to say that his work on Wrath of Khan really sent him on his way.
Sadly, we didn't get to hear everything he had to compose for us. He died on June 22, 2015, at the relatively young age of 61, when the plane he was piloting crashed in the Los Padres National Forest in Southern California. He left too soon, but his music lives on.