Probably the vaguest song identification request on here...?!

Probably the vaguest song identification request on here...?

I'm looking for a fairly famous classical song that is very eerie and very ominous. It begins with the strings playing 8 sets of 3 notes, and then afterwards the pattern continues while a choir sings a slow and sad melody. I've heard it in a lot of movies, but I've never found out what song it is. Again, it's fairly famous yet I doubt my details are specific enough, thanks in advance though.

Lacrymosa perhaps?