Doctor Who - Silence in the Library/Forest of the Dead (2008)
Noted as the first (or is that the last) appearance of River Song, this 2 part Doctor Who story also gave us the Vashta Nerada.
The Vashta Nerada are a microscopic swarm creature, indistinguishable from shadow that happen to have a taste for flesh. Capable of stripping a victim to the bone in seconds, if your wearing a space suit and they get in then you have a very good chance of ending up looking like this.
And if that's not bad in enough, when they're gathered in sufficient number, they manifest a hive mind and come lumbering after you in a very spooky way.
Its a couple of the finest episodes of new who you'll ever see so go and have a varda at the Vashta Nerada.