Easter
Easter was an Earth holiday usually celebrated in March or April.
Because it was always at a different time in the year, the Doctor had difficulty navigating his TARDIS to the correct date. The Tenth Doctor, however, landed on Easter 2009 in time to enjoy a chocolate Easter egg and to save Earth from an incursion of Stingrays. On this occasion, he also said that he had been present at the original Easter and intimated that the events were at variance with what humans believed. (TV: Planet of the Dead)
On Easter of 1996, seven-year-old Amelia Pond was praying to Santa Claus. She asked him to send someone to fix the crack in her bedroom wall just before the newly-regenerated Eleventh Doctor crashed in her garden on Earth and met her for the first time. (TV: The Eleventh Hour)
In a shared dream, the Twelfth Doctor coldly wished Santa Claus a happy Easter. Later, when Ashley Carter asked who Santa was, the Doctor sarcastically gave the options of tooth fairy and Easter Bunny. In a dream of Clara's set on Christmas Day, Danny Pink retorted in reply to her question, that it was Easter, and he was dressed in a Santa suit because he was "Father Easter". (TV: Last Christmas)
In the town of Christmas on Trenzalore, the Eleventh Doctor responded to Clara Oswald's question, "How can a town be called Christmas?" with, "How can an island be called Easter?" (TV: The Time of the Doctor)
