The Black Fang (黒い牙 Kuroi Kiba) is a group of assassins in Fire Emblem: Rekka no Ken located in Bern and founded by Brendan Reed. They originally set out to kill corrupt nobles and help the poor, but were later taken over from within by Nergal and his morphs. The original members of the Black Fang, before Nergal's takeover via Sonia's marriage to Brendan, are often referred to as the "Old Fang". Powerful members of the Black Fang were given titles, the greatest of which were the Four Fangs. During the course of the game, some members of the Black Fang are wiped out while others join Eliwood and company. Brendan Reed was the leader of the Black Fang until his death at the hands of Sonia, his second wife, who was actually a morph created by Nergal and used by him to influence and manipulate the group for his own nefarious purposes.
The four most powerful warriors in the Black Fang are known as the Four Fangs, who are made up of Lloyd, the White Wolf, Linus, the Mad Dog, Ursula, the Blue Crow, and Jaffar, the Angel of Death. Past members of the Four Fangs were Pascal, the Crazed Beast, and Jerme, the Death Kite. Legault, the Hurricane, while never one of the Four Fangs, was said to have power rivaling theirs.
- Brendan Reed - The founder of the Black Fang.
- Nergal - The Dark Druid who manipulates the Black Fang from behind the scenes
- Limstella - Nergal's most powerful morph, a Sage.
- Sonia - Brendan Reed's second wife and Nergal's second most powerful morph, a Sage.
- Ephidel - Marquess Darin's confidante and Nergal's third most powerful morph.
- Lloyd - "The White Wolf," a Swordmaster, elder son of Brendan and brother of Linus.
- Linus - "The Mad Dog," a Hero, younger son of Brendan and brother of Lloyd.
- Ursula - "The Blue Crow," a Valkyrie brought to the Black Fang by Sonia.
- Jaffar - "The Angel of Death," an Assassin who serves Nergal but joins Eliwood's company with Nino.
- Jerme - "The Death Kite," a cruel Assassin who guards their mountain fortress in Bern.
- Pascal - "The Crazed Beast," a Paladin and a former noble who slaughtered his own citizens.
- Legault - "The Hurricane," a Thief and Old Fang member who defects to Eliwood's company for safety.
- Uhai - "The Soaring Hawk," a Nomad Trooper who guards the forest on the shores of Valor.
- Teodor - "The Shadow Hawk," a Druid who confronts Eliwood's company in ancient ruins on Valor.
- Kenneth - "The Shrike," a deranged Bishop who guards their mountain fortress in Bern.
- Aion - "The Owl," a Sage who guards the entrance to the Dragon's Gate on Valor.
- Maxime - a Paladin who serves as Ursula's lieutenant.
- Cameron - a Paladin who guards the Dragon's Gate.
- Igor - a Myrmidon who serves directly under Linus but is interestingly not fought in-game.
- Zoldam - a Shaman who is sent from Valor to attack Fargus' ship and recover Ninian and Nils.
- Heintz - a Shaman who is sent to a fortress in northern Lycia to recover Ninan and Nils.
- Beyard - a Mercenary who serves as Ursula's subordinate.
- Boies - a Knight who serves as Ephidel's subordinate.
- Damian - a Paladin who was sent to kill Eliwood in Badon.
- Wire - a Knight who was sent to kill Hector in Ostia.
- Jan - a kind-hearted Brigand who acts as a surrogate uncle to Nino.
- Nino - a young girl from a talented family of Mages who was kidnapped by Sonia, who killed off the rest of her family, and pretended to be her real mother.