Having recently become interested in it, I know nothing.
In particular I'm interested in something dark with sharp contrasts between violent and calm sections.
Try Mozart's Requiem. The entire thing. There are melodically brutal sections like the Dies Irae movement sharply contrasted by the beauty of movements such as the Tuba Mirum or Hostias.
You also can't go wrong with Carl Orff's Carmina Burana. Everyone knows the Fortuna Imperatrix Mundi movement from that cause it's been used so much in movies and TV, but only classical fans have cared enough to listen to the whole thing.
Geinoh Yamashirogumi. They diid the soundtrack to Akira. I like it.
I second >>2's recommendations.
Also, Vivaldi's Four Seasons.
I totally forgot about Vivaldi... o.o;
Stravinsky's The Rite of Spring
Holst's The Planets. Try to get the one conducted by Stokowski, as it's the best.
lol mahler 2nd
Dvorak's New World Symphony is one of my favorites, as is Rimsky-Korsakov's "Scheherazade" suite (Rimsky-Korsakov is my favorite composer, actually)
Messiaen - Turangalila Symphonies
I recently saw this in the dutch concertbuilding in amsterdam, and it was fantastic, it starts kicking ass right away. also ondes Martenot is awesome