Fomortiis

Fomortiis, a giant horned demon known as the Demon King, is the final boss of Fire Emblem:the Sacred Stones.

In the year 3, the founders of Magvel trapped the Demon King's soul using the Sacred Stones. The stone of Grado (also known as the Fire Emblem) holds the soul of Fomortiis. Eight-hundred years later in year 803, Vigarde, the Emperor of Grado, dies and his son Lyon then tries to bring him back to life using the power of the Sacred Stones. Lyon succeeds, but in the process gets possessed by Formortiis.

Free of his prison, Fomortiis begins his reign of terror once more and invades Renais seeking to destroy its Sacred Stone using Vigarde and Lyon as his puppets. When he fails to locate the stone and the means to destroy it, he moves on to Frelia, where his generals Selena Fluorspar and Caellach Tiger-Eye easily overpower the Frelians and destroy their Sacred Stone.

Fomortiis sends Caellach to Jehanna, where he kills Queen Ismaire and destroys the stone. Afterwards, both generals Caellach and Valter are slain by twins Eirika and Ephraim in Jehanna's desert. Angered, Formortiis (still possessing Lyon) goes to stop the twins himself and destroy the stone they possess; he fails and retreats.

Soon after the twins' next battle according to the tale the player chooses, Fomortiis either tricks Eirika or takes the stone by force from Ephraim and thus destroys the stone of Renais. The twins venture to Rausten while Formortiis travels to his temple in Darkling Woods to revive his body. Formortiis then sends his last remaining general, Riev, to destroy the stone of Rausten and kill the Divine Emperor Mansel. Riev fails and retreats into Darkling Woods, where he is eventually slain and the twins gain entrance into the Black Temple of the Demon King.

Lyon is slain in the Black Temple and Fomortiis succeeds in resurrecting his body, but his soul is trapped within the Sacred Stone of Rausten. Eirika and Ephraim destroy Formortiis's body thus ensuring that he can never again be resurrected.