I'm not a huge Star Trek fan by any means, but I am a SciFi fan, and I was saddened to learn that Alexander Courage, who composed the original Star Trek theme, died this past month at the age of 88.
The original Star Trek is one of the pinnacles of Science Fiction media, whether you're a trekkie or not. It was so original, interesting and broke numerous barriers and has served as a benchmark for everything after it. The TV theme here is the perfect introduction.
Main Theme - Alexander Courage