Vashta Nerada

"Almost every species in the Universe has an irrational fear of the dark. But they're wrong. 'Cause it's not irrational. It's Vashta Nerada"

Meaning “the shadows that melt the flesh”, Vashta Nerada occur naturally on most planets – including Earth – in small clusters, like the dust in sunbeams. In The Library, the Doctor encountered an entire swarm of Vashta Nerada, stripping the flesh from numerous members of Mr Lux’s unfortunate crew. The Doctor brokered a deal with the creatures (who were using the animated remains of the crew in their flight-suits): if he could get the humans off the planet, the Vashta Nerada could remain in the “forests” of books.