Empress (Marco Polo)

The Empress of the court of Kublai Khan played only a very minor role in the adventures of the Doctor and his [companion]s in 13th century China. She was apparently aware and did not approve of the Emperor's penchant for gambling, as Kublai cautioned the Doctor to put away and hid the game they are playing when the Empress approached. (DW: Marco Polo)

Behind the scenes
The real Empress of Kublai Khan, named Chabi, actually played a more significant role in the court, being instrumental in the spread of Tibetan Buddhism in China and insuring that the Song rulers of southern China were well-treated after their conquest. She may also have tried, unsucessfully, to dissuade her husband from his ill-fated plans to conquer Japan.