"Father's Day" is the eighth episode of the first series of the British science fiction television programme Doctor Who, first broadcast on 14 May 2005 on BBC One. It was written by Paul Cornell and directed by Joe Ahearne.

In the episode, alien time traveller the Doctor (Christopher Eccleston) agrees to take his companion Rose Tyler (Billie Piper) back to the day her father Pete (Shaun Dingwall) died in 1987. When Rose intervenes and pulls her father out of the path of a car, time is wounded and dangerous Reapers attack, threatening to erase history. Pete eventually learns that to get rid of the Reapers, he must throw himself under the car that was originally meant to kill him.

Lead writer and executive producer Russell T Davies conceived "Father's Day" as an emotionally driven time travel story to explore Rose's character. He chose Cornell to write the episode; Cornell had been a successful writer of spin-off material during the years the programme was on hiatus. The monster element of the story was expanded based on suggestions from Cornell and BBC Head of Drama Jane Tranter, and the Reapers went through many designs. The episode was filmed in November 2004 at St Paul's Church and streets in Cardiff. "Father's Day" was watched by 8.06 million viewers in the United Kingdom and received generally positive reviews. Critics praised the focus on character and emotion.

The episode opens with a flashback of Jackie Tyler telling a younger Rose about her father Pete, who died in a hit-and-run accident on the way to a friend's wedding.

In the TARDIS, the Doctor agrees to take Rose to the day her father died so that she can be there when it happens. Upon their arrival in London on Saturday 7 November 1987, they witness the accident, but Rose is unable to move when The Doctor tells her to go comfort her dying father. Rose asks the Doctor if she can try again, and the Doctor allows it but warns Rose to not run until their former selves have left to prevent a paradox. As the accident is about to happen, Rose suddenly runs out and pushes Pete aside, saving his life. The younger versions of the Doctor and Rose vanish. Rose and the Doctor fight about her actions, with the Doctor rebuking her for potentially damaging the timeline. The Doctor takes Rose's TARDIS key back and storms off without her. Rose decides to go with Pete to the wedding, while the Doctor walks back to the TARDIS only to find that it is now an empty shell. Strange flying beasts called Reapers appear and begin consuming people.

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