euhemerize
To create mythology and legends from ancient historical figures and events.
Near-synonym: deify (synonymous when personages are the direct objects)
Where it comes from
From euhemerism + -ize, ultimately from Latin Euhēmerus, from Ancient Greek Εὐήμερος (Euḗmeros), an ancient Greek Sicilian Skeptic who proposed most or all mythology derived from historical figures and natural events which received supernatural characteristics only through retelling.
Adapted from the Wiktionary entry euhemerize (CC BY-SA 4.0).