Nightmare Fuel / The Avengers (2012)

• Hawkeye needs the eye scan of a certain man to open a door that holds a meteorite shard. He gives a hand held scanner to Loki, who proceeds to crash the guy's party, hold him down over a decorative slab in front of the terrified crowd, and - possibly not understanding precisely how the thing works, probably just for kicks - ram the scanner right into the guy's eye. Add the other patrons screaming in horror and the sounds of the process (both the machine whirring and what seems to be the guy's face being squished) and it's enough to make anyone squirm.
• The Chitauri may not be so straight-up terrifying once we see them, but when the NYC portal is opened and we see the other side, for a moment it's just a black space filled with glowing purple lights and hissing, chirping noises that sound like something straight out of Alien.