Easter Special
From Tardis Wiki, the free Doctor Who reference
An Easter special of Doctor Who is an episode which airs outside of the regular run during the Easter weekend.
There have been two Easter specials as of 2022. The first was the 2009 special, Planet of the Dead, which aired on the Saturday that fell between Good Friday and Easter Sunday, while the second was Legend of the Sea Devils, the 2022 special, which aired on Easter Sunday itself, taking advantage of the show's then-regular Sunday evening timeslot.
