Goblin

Throughout Doctor Who Goblins have been mentioned to exist (DW: Midnight, The Pandorica Opens, A Good Man Goes to War). According to legend they can be powerful enough to be locked inside the Pandorica.

A species may exist called Goblin Men, (DW: Midnight) from Christina Rossetti's poem "Goblin Market"; she may have encountered a goblin-like aliens that caused her to write the poem. Dee Dee Blasco quotes the poem:

"We must not look at goblin men,

We must not buy their fruits:

Who knows upon what soil they fed

Their hungry, thirst roots?"