If you've seen Breaking Dawn: Part 2, you already know what we're talking about. Yes — the shrill vampire scream laugh from Michael Sheen eclipses any other startling event that could pop out of the conclusion of the Twilight franchise. It's magical, so enjoy.
If you want to find out even more information behind the Aro laugh, here's a little interview where Michael Sheen explains everything. There's a backstory, obviously, Sheen doesn't take his vampire shrieks lightly.