Night on a Bare Mountain is probably one of Mussorgsky's better known works amongst people who don't make it a point to listen to classical music regularly. If you, by chance, have no idea what piece I'm talking about, here's a clip:
There are many other famous classical works used for Halloween, and many of their histories aren't seeded in anything scary or evil at all. Bach's Toccata and Fugue in D Minor is one of these "scary" pieces of music (especially if you're performing the Wind Ensemble orchestration):
If anyone knows that "girls just wanna have fun" it's me, and you may not have the time to sit down and listen to Mussorgsky and Bach, but when you're out and about this weekend all dressed up celebrating all of the evil spirits of the fall and partaking of various adult "candies", take just a moment to think about the classical music that helps to promote this time of year - I know that me and all of the other school girls will!
Listening to: Thriller, Michael Jackson