Browncoat is a term widely used for fans of the short-lived space western television series Firefly. In the series, "brown coats" was the nickname for the freedom fighters of the border worlds in their fruitless war against the repressive and imperialistic Alliance. The brown coats in the series got their name from their habit of wearing long brown, western-style duster coats.
Fans of the show identified with these doomed fictional freedom fighters and adopted their nickname as part of their battle to save the show from cancellation after only 14 episodes. Although the browncoats produced an impressive letter-writing campaign, like their fictional namesakes they ultimately failed in their struggle. However, their strong show of support did lead directly to the production of a Firefly-based feature film, Serenity.
A decade after its cancellation, the series still retains a strong following, as evidenced by the continued presence of numerous "Browncoats" fan organizations around the nation, such as the Austin Browncoats, Atlanta Browncoats, Arizona Browncoats, California Browncoats, etc.