Fallen Heroes

Fallen Heroes are a category of Heroes in Fire Emblem Heroes. The characters in question are usually 5-Star locked and are normally possessed in some form. All art of them featured purple flames.

Chiaki Sakura Rose is a fan of the concept, for unknown reasons.

Listing
Year 1: Fallen Heroes (February 2018) Year 2: Darkness Within (May 2019) Year 3: Dark Burdens (May 2020)
 * Robin: Fell Reincarnation: The Ylissean tactician Robin with body and soul ruled by the Fell Dragon, Grima. Appears in Fire Emblem Awakening.
 * Hardin - Dark Emperor: Emperor of the Holy Empire of Archanea. Known as the Dark Emperor due to his bloody reign. Appears in Fire Emblem: Mystery of the Emblem.
 * Celica - Imprisoned Soul: Celica's form as a witch after giving her soul to Duma. It seems her old memories occassionally rise to the surface. Appears in Fire Emblem Echoes: Shadows of Valentia.
 * Takumi - Empty Vessel: Prince of Hoshido who wields the evil bow Skadi. While his love for his homeland remains, he was forced to become a servant of one of the First Dragons. Appears in Fire Emblem Fates.
 * Robin: Fell Vessel: The Ylissean tactician Robin with body and soul ruled by the Fell Dragon, Grima. Appears in Fire Emblem Awakening.
 * Mareeta - The Blade's Pawn: Foster daughter of Eyvel, mistress of Fiana. As part of a wicked plot, she laid hands on a cursed sword. Appears in Fire Emblem: Thracia 776.
 * Berkut - Purgatorial Prince: Heir presumptive to the Rigelian throne. Fell into a deep despair when the truth about Alm came out. Gave his betrothed's life to Duma to obtain power. Appears in Fire Emblem Echoes: Shadows of Valentia.
 * Corrin - Wailing Soul: Unfortunate soul torn between both Nohr and Hoshido, overtaken by the power lurking in her blood. Appears in Fire Emblem Fates.
 * Tiki - Torpid Dragon: Princess of the Divine Dragon tribe. She was taken to the Fane of Raman and, under Gharnef's control, incinerated all those who entered. Appears in Fire Emblem: Mystery of the Emblem.
 * Delthea - Tatarrah's Puppet: A naturally gifted mage who has fallen under the control of Tatarrah, of the Duma Faithful. Appears in Fire Emblem Echoes: Shadows of Valentia.
 * Corrin - Bloodbound Beast: A prince born in Hoshido but raised in Nohr. Within the blood coursing through his veins, a brutal presence lies sleeping. Appears in Fire Emblem Fates.
 * Lyon - Demon King: Prince Lyon of Grado, having become a vessel for the Demon King Fomortiis's power. It is uncertain who directs his heart. Appears in Fire Emblem: The Sacred Stones.
 * Julia - Heart Usurped: Inheritor of the Book of Naga. Manipulated by Manfroy, she has grown hostile toward Seliph. Appears in Fire Emblem: Genealogy of the Holy War. 
 * Ike - Zeal Unleashed: Leader of the Greil Mercenaries. Overwhelmed with negative energy, the power is enough for him to lose control. Appears in Fire Emblem: Radiant Dawn.
 * Ashnard - Mad King: The thirteenth ruler of Daein. Plotting to wield his power to rule without opposition, he plunges the whole continent of Tellius into war. Appears in Fire Emblem: Path of Radiance.

Trivia

 * Ike is the only Fallen Hero to not be based off an in-game event, instead being based off art from Fire Emblem Cipher.
 * Robin - Fell Vessel is the only Fallen Hero not to be introduced in a New Heroes banner or Grand Hero Battle, instead being a Legendary Unit.
 * Every wave of Fallen Heroes comes with a character not featured in Heroes. At the moment these are Hardin, Mareeta, and Ashnard.
 * Mareeta was added as her own unit in December 2019's World of Thracia + Peony banner.