Breath of Fire features eight permanent playable characters, including Ryu, a member of the Light Dragon family whose sister has been captured by the Dark Dragons; Nina, Princess of Winlan, who joins Ryu after he helps saves her father's life; Bo, a wolfish hunter who shares a common enemy with Ryu; Karn, a crafty thief who can pick any lock and disarm any trap; Gobi, a Manillo who was expelled from his clan because he was considered too greedy even for his kind; Ox, a blacksmith who was forced to labor on a secret weapon; Bleu, an immortal sorceress with the lower body of a snake; and Mogu, a mole-like creature who is trapped inside his own nightmare as the result of a magician's spell.
All of the main characters hold a grudge toward the Dark Dragons in general and their Emperor, Zog, in particular. Other antagonists include Zog's top lieutenant, Jade, who overpowers Ryu's sister during the game's opening. Jade's henchmen are his Four Devas, each of whom oppose Ryu and his team: Cort, a mad scientist; Cerl, a half-breed magic user who resents her past mistreatment by humans; Mote, a wizard who has the power to terrorize people in their dreams; and Goda, an armored goliath.