The music is just another actor?

Not being one of those people who were traumatized by the movie, I allowed Mo to watch "Jaws".

I have since learned that many otherwise reasonable people, including Mo, were really freaked out by this movie.

Which led to a big conversation today about film-making:

Me: It's a movie, it's all make belive, you know that right?
Mo: Right.....
Me: You aren't afraid of puppets are you?
Mo: No. That's silly.
Me: That shark was just a puppet.
Mo: But what about those people that got eaten?
Me: They were actors. People who were hired to pretend to be someone else.
Mo: Oh.
Mo: But what abou that "duh duh" sound?
Me: That was just the music. They hired someone to write scary music.
Mo: What makes it scary?
Me: Uh...... it sounds like your heart when you get scared and..... uhhhh...

Blahblahblah. (The conversation was a bit more involved than that but I'm trying not to be a bore.)

Then we had to pretend that I went to him to have him compose music for a movie that involves shark puppets eating actors.

Mo: So the music is really just another actor?
Me: Exactly!


Later to myself:

Hell yeah, exactly! Music is just another actor. I never thought of it like that but really it is true.

So.

What movies can you think of where the music was a good actor?

A bad actor?

Not an actor at all but a soundtrack? (Not that there's anything wrong with that.)

Thanks!