Science fiction fandom other groups including LGBT communities, libertarians, neo-pagans, and space activist groups like the L5 Society, among many others. Some groups exist almost entirely within fandom but are distinct and cohesive subcultures in their own rights, such as filkers, costumers, and convention runners (sometimes called "SMOFs"). Fandom encompasses subsets of fans that are principally interested in a single writer or subgenre, such as Tolkien fandom, and ("Trekkies"). Even short-lived television series may have dedicated followings, such as the fans of Joss Whedon's "Firefly" television series and movie "Serenity", known as Browncoats. Participation in science fiction fandom often overlaps with other similar
Firefly (TV series) them to be broadcast, as well as seven episode commentaries, outtakes and other features. The DVDs feature the episodes as they were shot in 16:9 widescreen, with anamorphic transfers and Dolby Surround audio. By September 2005, its DVD release had sold approximately 500,000 copies. The series was re-released on Blu-ray Disc on November 11, 2008, comprising three discs; exclusive extras to the Blu-ray release include extra audio commentary from Joss Whedon, Nathan Fillion, Alan Tudyk and Ron Glass for the episode "Our Mrs. Reynolds", as well as an additional featurette, ""Firefly" Reunion: Lunch with Joss, Nathan, Alan and Ron". Many