Duck

Ducks were a species of bird. People fed bread to them. Hex considered that the life of a duck must be nice and simple. (AUDIO: A Death in the Family)

A duck got into the Doctor's TARDIS, but the Seventh Doctor got it to leave. (TV: Silver Nemesis)

Leadworth had a duck pond which didn't have any ducks, yet Amy Pond still knew that it was a duck pond. (TV: The Eleventh Hour) The Eleventh Doctor later realised that the ducks had been erased from history by cracks in time. (TV: Flesh and Stone)

The Doctor, Amy and Rory later had a picnic near a duck pond in New York City's Central Park. (TV: The Angels Take Manhattan)

Clifford Banks resembled a human with a duck's bill. (COMIC: Interstellar Overdrive)