Not much more to add about the TV show "Firefly", except that co-creator Joss Whedon thought of it as a space western, and the characters could well be said to be "space cowboys". Part of the appeal of the show was that there were NINE main characters: 5 crew (captain Mal, first officer Zoe, pilot Wash (Zoe's husband), mechanic Kaylee, and mercenary Jayne) and 4 passengers ("companion" Inara (similar to a geisha -- with an unrevealed backstory), "shepherd" Book (a minister -- with an unrevealed backstory), ship doctor Simon (his services pay for his and his sister's travels), and crazy psychic River (the sister -- also with an unrevealed backstory, and the Alliance is hunting her).
Oh, and in addition to the 14 hour-long episodes of the TV series for Fox (about half a season worth), there was a Whedon-produced-and-directed 2-hour theatrical movie for Universal entitled "Serenity", which was set about six months after the end of the TV series and wrapped up one of the main storylines of the show (the unrevealed backstory behind River's bizarre behavior and the determination of the Alliance to recapture her). Because of the different studios involved, these items are never packaged together.
Whedon also supervised a series of "Serenity" comic books that filled in some more of the unfilmed plot ideas from the show's backstory, although whether that is more than a curiosity depends upon how absorbed a person becomes in that world.
https://en.wikipedia.org/wiki/Firefly_(TV_series)
https://en.wikipedia.org/wiki/Serenity_(2005_film)
https://en.wikipedia.org/wiki/Serenity_(comics)