Pottery painter (The Angels Take Manhattan)

In 221 BC China, a pottery painter painted vases which would later be regarded as Qin dynasty artefacts. On the Eleventh Doctor's request, he painted "Yowzah!" in period Chinese on the base of one of his vases. That vase was later in private possession of New York City art collector Julius Grayle, by 1938.

This sent a message to River Song, which allowed the Doctor "landing lights" for his TARDIS, so he could come and rescue her. (TV: The Angels Take Manhattan)

Behind the scenes
Though not credited, the Chinese pottery painter was played by Clem So.