"Past Prologue" is the third episode of the American science fiction television series Star Trek: Deep Space Nine, broadcast during the first season. It originally aired in broadcast syndication beginning on January 10, 1993. The episode was written by Katharyn Powers, with additional elements added by executive producer Michael Piller and co-producer Peter Allan Fields. It was directed by Winrich Kolbe.

Set in the 24th century, the series follows the adventures on Deep Space Nine, a space station located near a stable wormhole between the Alpha and Gamma quadrants of the Milky Way Galaxy. In this episode, a Bajoran terrorist seeks asylum aboard the station from pursuing Cardassians, publicly renouncing his past violent ways. He begins liaising with the Duras sisters (Barbara March and Gwynyth Walsh), leading to suspicion that he was planning further acts of terrorism and causing Major Kira Nerys (Nana Visitor) to consider her loyalties.

The episode introduces the character of Garak, played by Andrew Robinson, who would return in the second season and made continued appearances throughout the series. The character's traits were developed by Robinson, who was praised for his work by Kolbe. "Past Prologue" was the second most watched episode of the season, receiving a Nielsen rating of 13.4 percent. It was received positively by critics, who praised the introduction of Garak, although it was suggested that the plot was predictable due to the need to maintain the status quo at the end of the episode.

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