Buffy the Vampire Slayer - episode 3 "the Witch"

Strange events are occurring at Sunnydale High.  Cheerleaders are being rendered incapable of performing with the cheer squad through various supernatural means.  The poor girl depicted here is knocked out of the running when her mouth mysteriously vanishes from her face.  You can't cheer if you haven't got a mouth, right?

And here's a concept sketch and a picture of the actress after the makeup was applied.