Doctor Who: The Unquiet Dead (2005)
Unless I'm forgetting something, this is the only episode of the revamped Doctor Who series set at Christmas that wasn't produced as a "Christmas special." It's only the third Christopher Eccleston episode, and marks the first time him and Rose went into the past. The past they wind up in is 1869. It's Christmas Eve and - despite trying for Naples - the TARDIS takes them to Cardiff. As is always the case, there's more going on than a celebration. An undertaker in the city can't seem to keep the dead to stay still: they've picked up a habit of rising up and making trouble. One, an old woman, kills a grieving family member, climbs out of her coffin, and proceeds with her plans for the evening: catching a live reading of A Christmas Carol performed by the author, who is quickly pulled into the story. Also of note is the undertaker's psychic assistant, a woman about Rose's age who's developed a connection with the beings responsible.