23 December

On 23 December 1892, Clara Oswin Oswald first met the Eleventh Doctor in London, when she asked him about the snowmen. She also first found the TARDIS exterior staircase, and, by extension, the TARDIS itself. (TV: The Snowmen)

23 December was the date of the Crystal Feast in Sardicktown and on the planet Ember, a winter celebration. (PROSE: Time Traveller's Diary)

In 1861, the Fifth Doctor and Turlough assisted Mrs Elkins in defending her Virginia farmhouse from a group of American Civil War deserters led by Lucius Casler. (PROSE: Comforts of Home)

In 1968, the Seventh Doctor and Ace arrived in the village of Crook Marsham only to become embroiled in a mystery involving disappearing townsfolk. Ultimately, the answer to the puzzle puts the time travellers in direct conflict with the mysterious Sentience. (PROSE: Nightshade)

According to a calendar on the Snowcap base, 23 December 1986 was a Tuesday. (TV: The Tenth Planet)