Cleopatra

Cleopatra VII was queen of Egypt and the consort of Mark Anthony. (PROSE: State of Change) She was Greek, although it was a common mistake to think she was Egyptian. Cleopatra was abducted by Momus while she had Mark Antony waiting in her studio. (PROSE: The Lonely Computer)

The Fourth Doctor claimed to have learned swordsmanship from a captain in Cleopatra's bodyguard. (TV: The Masque of Mandragora, PROSE: The Shadow of Weng-Chiang)

The Fifth Doctor reported to have met Cleopatra at some point. He described her as having "the succour and grace of a carpet flea." (AUDIO: Loups-Garoux)

The Sixth Doctor and Peri Brown watched Cleopatra's barge on the River Nile. (PROSE: State of Change)

The Tenth Doctor hinted that he or an earlier incarnation had had some sort of relationship with Cleopatra, and called her "Cleo". (TV: The Girl in the Fireplace) He later told Donna Noble that accounts of her beauty were greatly exaggerated. Indeed, he said that she could only be "the most beautiful woman in the world" if her bedchamber were expanded to the size of the Earth, and "all her handmaidens had had the day off". Nonetheless, the Doctor intimated that he had actually seen her bedchamber. (PROSE: Ghosts of India)

Later references
In 102 AD, River Song pretended to be Cleopatra and used her hallucinogenic lipstick on a Roman soldier to fool him, even though the real Cleopatra had died a hundred thirty-two years before River arrived. (TV: The Pandorica Opens)

Alternate timelines
On the duplicate Earth known as Terra Nova, Cleopatra and Mark Antony won the Battle of Actium and had three children. (PROSE: State of Change)

In an alternate timeline in which all of history happened at the same moment because River Song refused to kill the Eleventh Doctor, Cleopatra met with Holy Roman Emperor Winston Churchill in Gaul and River Song got her to give Amy Pond the Great Pyramid in Giza by using hallucinogenic lipstick and a gun. (TV: The Wedding of River Song)

Behind the scenes

 * According to The Brilliant Book 2012, a book that contains non-narrative based information, the alternate Cleopatra was on Facebook. She was friends with River, Churchill and Napoleon Bonaparte. She was a fan of Vincent van Gogh and Silurian medicine and played live chess with Joseph Stalin; she also read the book Murder on the Sky Orient Express and joined the online groups Can I get 6,000,000,000 people to join this group before 5.03pm??? and I'm not being funny but I think this is all the Doctor's fault!