"a traditional or legendary story, usually concerning some being or hero or event, with or without a determinable basis of fact or a natural explanation, especially one that is concerned with deities or demigods and explains some practice, rite, or phenomenon of nature."Some peoples came to see their own mythology as "true" stories whereas fables were considered to be fiction. A Greek mythologist, Euhemerus, who lived about 1700 years ago, first put out the idea that myths were based on actual events and people. According to Euhemerus, as these stories were based down, they were embellished until the characters become god-like beings. Whether or not the stories have any basis in reality, it's easy to see why people would have created these stories to explain things for which there was no other explanation.
Another theory is that myths have their basis in allegory, particularly for natural phenomenon or spiritual concepts. Yet another theory contends that myths were the result of "personification of inanimate objects and forces."
Regardless of how "myth" is defined or what their genesis was, they make wonderful stories that have clearly stood the test of time. What do Shakespeare and George Clooney have in common? Mythology. Shakespeare borrowed heavily from Greek mythology in writing him plays. Clooney starred in "O Brother, Where Art Thou?" which was based on The Odyssey.