Marilyn Monroe
Marilyn Monroe was an American celebrity in the mid 20th century. In 1952, she met the Eleventh Doctor at a Hollywood party, and he "accidentally" accepted a marriage proposal from her. He tried to avoid it, but ended up leaving the party with her to get married, apparently making her the Doctor's spouse. Marilyn got the Doctor's phone number and later attempted to call him, though he denied the legitimacy of the chapel. (TV: A Christmas Carol)
River Song mentioned her among the other spouses of the Doctor. (TV: The Husbands of River Song)
Behind the scenes
In HOMEVID: Good Night, the Doctor calls a farewell to an unseen River Song and asks her to "tell Marilyn she'll have to use the biplane".