- Due to popularity of Arthurian legends, many unrelated Welsh and Breton folk tales later had some Arthurian elements and trappings added, such as with such as Tristan and Iseult.
- Older Than Feudalism: The Classical tale of Jason and the Argonauts brought together many mythological heroes in a sort of Justice League Ancient Greece. "Hero" in Classical Mythology was an awfully vague term (as Larry Gonick put it, heroes aren't necessarily heroic, just excessive), and since the mission was to steal an item (the Golden Fleece) "Justice League" isn't a terribly good name for them....
- Maid Marian, the shepherdess, featured in many pastoral plays popular at May festivities. Then there was a fad for Robin Hood plays. Then someone put the two characters together. It worked so well that Maid Marian is best known as a Robin Hood character, even though her independent existence predates him.
Cross Over / Mythology