Frankish mythology comprises the mythology of the Germanic tribe of the Franks, from its roots in polytheistic Germanic paganism through the inclusion of Greco-Roman components in the Early Middle Ages. This mythology flourished among the Franks until the conversion of the Merovingian king Clovis I to Nicene Christianity (circa 500), though there were many Frankish Christians before that. After that, their paganism was gradually replaced by the process of Christianisation, but there were still pagans in the Frankish heartland of Toxandria in the late seventh century.

Echoes of Frankish paganism arise in the primary sources, but their meaning is not always clear. Modern scholars vary widely about the interpretation, but it is likely that Frankish paganism shared most of its characteristics with the other varieties of Germanic paganism, such as placing altars in forest glens, on hilltops, or besides lakes and rivers, and consecrating woods. Generally, Germanic gods were associated with local cult centres and their sacred character and power were associated with specific regions, outside of which they were neither worshipped nor feared. Other deities were known and feared and shared by cultures and tribes, although in different names and variations. Of the latter, the Franks may have had one omnipotent god Allfadir ("All Father"), thought to have lived in a sacred grove. Germanic peoples may have gathered where they believed him to live, and sacrificed a human life to him.