Without the maniacal laughter, our favorite movie villains would just be everyday assh*les with arbitrary axes to grind. So let's pay homage to some of the best calamitous cackling ever to grace (plague?) the silver screen.
Don't look now but while you were busy having a good chuckle, your nemeses just wriggled free of their bonds and turned off the laser/disarmed the bomb/administered the antidote/generally saved the day. He who laughs last...probably should've been paying closer attention.