Here's the final showdown betwen Johnny Depp and Charlize Theron, from 1999's The Astronaut's Wife, when the slow-boiling thriller suddenly turns into a bodacious monster movie. I love Johnny Depp's weird slurred-voice alien-monster acting. It's actually a super disturbing scene, as Depp's ownership of Theron's body suddenly goes from subtle creepitude to full-on monster creepitude.
It's great that Charlize had time to get such a nice pedicure while her husband was getting lost in space and then came back as an alien fiend who knocked her up with his demon babies. The little flashes of overexposed fetuses looking vicious are the total epitome of pregnancy horror. Charlize plans to electrocute herself, terminating the pregnancy the hard way. But at the last minute, she decides to zap Johnny instead, which turns out to be a bad, bad idea.