Star Trek: Deep Space Nine (abbreviated as DS9) is an American science fiction television series created by Rick Berman and Michael Piller. The fourth series in the Star Trek media franchise, it originally aired in syndication from January 3, 1993, to June 2, 1999, spanning 176 episodes over seven seasons.Set in the 24th century, when Earth is part of a United Federation of Planets, its narrative is centered on the eponymous space station Deep Space Nine, located adjacent to a wormhole connecting Federation territory to the Gamma Quadrant on the far side of the Milky Way galaxy.

Following the success of Star Trek: The Next Generation, Paramount Pictures commissioned a new series set in the Star Trek fictional universe. In creating Deep Space Nine, Berman and Piller drew upon plot elements introduced in The Next Generation, namely the conflict between two alien species, the Cardassians and the Bajorans. Deep Space Nine was the first Star Trek series to be created without the direct involvement of franchise creator Gene Roddenberry, the first set on a space station rather than a traveling starship and the first to have an African American as its central character: Starfleet Commander, and then Captain, Benjamin Sisko (played by Avery Brooks).

Changes were made to the series over the course of its seven-year run. In the third season, the starship USS Defiant was introduced to enable more stories away from the space station, and the fourth added Worf (Michael Dorn), a character who originated on The Next Generation, to the main cast. The final three seasons deal with a story arc, that of the war between the Federation and an invading Gamma Quadrant power, the Dominion. Although not as popular as The Next Generation, Deep Space Nine was critically well-received. Following the success of Deep Space Nine, Paramount commissioned Berman, Piller and Jeri Taylor to produce Star Trek: Voyager, which began in 1995. During Deep Space Nine's run, various episode novelizations and tie-in video games were produced. After the show ended, various novels and comics continued the crew's adventures.