Marco Polo

Marco Polo (born 1252) was a Venetian trader and explorer who traveled with the First Doctor and his companions.

Biography
Polo, with his father and uncle, left for Cathay in the year 1271.By his twenty-fifth birthday in 1277, he had come into the service of Kublai Khan. In 1287, Marco, his brother and uncle asked the Khan to be permitted to return home. The Khan refused.

Polo encountered the First Doctor, Ian, Barbara and Susan on the Plain of Pamir in 1289 and promptly seized the TARDIS as a gift for the Khan. He hoped it would be sufficiently impressive to buy his way out of the Khan's service so he could return home. The Doctor and his companions were forced to make a long overland journey with Polo, during which time they got to know him well. (TV: Marco Polo)

Alternate timeline
In a alternate timeline which may have been invalidated by Big Bang Two, Polo purchased the Pandorica. As always, an Auton reconstruction of Amy Pond's fiancé, Rory Williams, accompanied the box. (TV: The Big Bang)

Minor references
Astrolabus claimed he had an appointment in Cathay with Marco Polo. (DWM: Voyager)

Behind the scenes
Marco Polo offers a clear example of how Doctor Who universe history differs from real world history. According to real world history, Polo was born in 1254. However, the first episode of Marco Polo explicitly tells us that he turned twenty-five in 1277, meaning that in the Doctor Who universe Marco Polo was born in 1252.