Gustavo Santoalalla is the best composer you've never heard of…unless you're a total film music buff. Santoalalla composed the scores for Brokeback, Babel (2006), and the video game The Last of Us (2013). All of these works featured panoramic landscapes and high drama, with a score to match.
Santoalalla recorded three solo albums before transitioning to cinematic scores—he's heavily influenced by Mexican and South American rock. He actually composed the music before the film was shot, which is the opposite of how most films are scored.
In fact, Santalalla's haunting guitar music was used as an inspiration for many of the movie's scenes. His soft, subtle tracks deepen the film's tender, quiet scenes.
Oddly, Brokeback Mountain was reworked as an opera in Madrid, but it threw out all of Santoalalla's music. The opera took a different approach than Santoalalla, creating music described by critics as "relentlessly busy" and "predictable." (Source)
Ouch. Should have stuck with the Argentinian guitar.