With the success of The Next Generation, another “Star Trek” spin-off was planned. Instead of being placed on a starship like the previous series and movies, this would be set aboard a space station with an all new cast and crew.
Deep Space Nine was the third live-action Star Trek series after The Original and The Next Generation. It was the first Star Trek series created by Rick Berman and Michael Piller rather than by Gene Roddenberry. It was also the only series to air alongside another Star Trek production throughout its entire run, airing alongside Star Trek: The Next Generation from 1993 until 1994, and then with Star Trek: Voyager from 1995 until 1999.
Also starring Rene Auberjonois, Nana Visitor, Terry Farrell, Armin Shimerman, Colm Meaney, Siddig El Fadil (later credited as Alexander Siddig), Nicole de Boer (Season 7), Michael Dorn (Season 4).
The show was known for its complex characters and storylines, engaging battle scenes and darker (less Utopian) atmosphere.
Star Trek: DS9 episode In Pale Moonlight is the darkest episode in the series and in Star Trek history. The episode represents the polar opposite of Gene Roddenberry’s utopian future of humanity. If anything this is what made DS9 stand out to the other Star Trek shows and considered by many to be the best.
Deep Space Nine remained a fan-favourite series throughout its seven-year run, with reviewers consistently lauding the series for its bold shift in tone from The Next Generation. Most notable among such changes was the concept of inter-personal conflict – something which Gene Roddenberry himself was said to have forbidden.
Source Memory Alpha