In Fire Emblem Warriors stronger variants of generic Manaketes are also known by the name Fafnir (Japanese: ファヴニルFafnir) though they don't appear to particularly resemble the similarly named appearance in Echoes: Shadows of Valentia.
In Norse mythology, Fáfnir is a son of the dwarf king Hreidmar who killed his father in order to claim Andvari's gold, and then transformed into a dragon in order to guard it. As part of a plot by his brother Regin to avenge their father's death, he was slain by Sigurd.