The Turk was a machine created in the 18th century. It took the form and, apparently, mind of a human. The grand masters of Europe could play chess against the machine. (PROSE: The Adventuress of Henrietta Street)
The description of the Silver Turk's performances at the 1873 Vienna Exposition reminded the Eighth Doctor of this earlier Turk. (AUDIO: The Silver Turk)
Behind the scenes
The Turk served as inspiration for Russell T Davies in devising the Clockwork Droids that appeared in 2006's The Girl in the Fireplace. (DWMSE 14) The title of the audio story The Silver Turk also refers to the machine.