What's your pick for most terrifying laugh in a horror movie?

For me it's the end of From Beyond. The whole movie is nuts, and the last act is absolutely insane lol.

After she jumps out the window, and all the people are gathering, she's clearly in pain and visibly distraught. Her line at the end is gruesome enough, but when she starts crying and slips straight into madness, that laugh is just so crazy. I get chills every time I hear it.