A surprising question, but for me a stand-out movie soundtrack would have to be the one that accompanied Dredd.
It was a very atypical soundtrack, but fit the movie perfectly and I think actually uplifted the scenarios. Admittedly listening to it out of context might sound a bit strange to your ears, since it's such a heavy and at times even ear-wrenching soundtrack (the electronic patch instrumentation is deliberately very, very rough), it couldn't have fit the horrific and at times slightly surreal settings of the film better.
Aside from that, I'm gonna have to go in on the guilty pleasure points on the godawful funk bass and drumming that accompanied the gleefully lousy American Ninja movies - especially the original, the stand-out best-worst - if anyone's ever had the dubious fortunes of seeing them.
As for a particular composer, Ennio Morricone is the man. Trite it may seem now, but the fact is - he made it 'trite' in the first place, haha! All credit. And who doesn't love a Western, or at least has a grudging liking for them?