 Nathan Fillion as Malcolm " Mal " Reynolds — the owner and captain of Serenity and former Independent sergeant in the pivotal Battle of Serenity Valley . Malcolm grew up on a ranch , and was raised by his mother and the ranch hands . In the Unification War , he fought for the Independent Army , the " Browncoats " , as a platoon sergeant in the 57th Overlanders . He is cunning , a capable leader and a skilled fighter . Mal 's main character drive is his will for independence . While he is not above petty theft , smuggling or even killing to maintain his free lifestyle , he is generally honest in his dealings with others , fiercely loyal to his crew and closely follows a personal moral code . He is openly antagonistic toward religion . 
