Several kinds!
The grandfather paradox is perhaps the most well-known type of time-travel paradox, and "Doctor Who" has explored it in several episodes. In "Father's Day," Rose Tyler saves her father from being hit by a car, which creates a series of events that ultimately lead to the destruction of the universe. This paradox highlights the danger of meddling with past events, as even the smallest change can have catastrophic consequences.
The ontological paradox is perhaps the most mind-bending type of paradox, as it involves events in the past being caused by actions in the future, but ultimately leading to the future traveler's own existence.
Here's list of Doctor Who episodes time travel paradox
- "Father's Day" (Season 1, Episode 8) - In this episode, Rose Tyler goes back in time to save her father from being hit by a car, which creates a paradox that threatens to destroy the universe.
- "Blink" (Season 3, Episode 10) - This episode features the ontological paradox, as the Doctor sends messages back in time to Sally Sparrow, who then uses the information to help the Doctor in the future.
- "The Girl in the Fireplace" (Season 2, Episode 4) - This episode features a temporal paradox, as the Doctor and his companions travel back in time to eighteenth-century France and encounter a woman who has been communicating with them from the future.
- "The Waters of Mars" (Season 4, Special Episode) - In this episode, the Doctor tries to change a fixed point in time, which leads to a series of events that threaten to create a paradox and destroy the future.
- "The Time of Angels" (Season 5, Episode 4) - This episode features a bootstrap paradox, as the Doctor and his companions encounter a recording of the Doctor's voice from the future that he hasn't recorded yet.
- "Before the Flood" (Season 9, Episode 4) - This episode features another bootstrap paradox, as the Doctor realizes that a piece of information he obtained from the future was actually given to him by his own past self.
- "Hell Bent" (Season 9, Episode 12) - In this episode, the Doctor creates a temporal paradox by going back in time and rescuing his companion Clara from death, which ultimately leads to the destruction of Gallifrey.
- "The Wedding of River Song" (Season 6, Episode 13) - This episode explores the dangers of the grandfather paradox, as the Doctor realizes that his own death is a fixed point in time, and if he tries to change it, he will create a paradox that could destroy the universe.
- "Utopia" (Season 3, Episode 11) - In this episode, the Doctor and his companions travel to the end of the universe and encounter a man who claims to be the last of the Time Lords, but is actually a future version of the Doctor himself.
- "Heaven Sent" (Season 9, Episode 11) - This episode features a time loop, as the Doctor is trapped in a castle that resets every time he dies, and must find a way to break the cycle and escape.









