The Monomyth is a story formula that is – apparently – found in too many narratives from around the world. The Wikipedia page on the monomyth is a good laugh:

In a monomyth, the hero begins in the ordinary world, and receives a call to enter an unknown world of strange powers and events. The hero who accepts the call to enter this strange world must face tasks and trials, either alone or with assistance. In the most intense versions of the narrative, the hero must survive a severe challenge, often with help. If the hero survives, the hero may achieve a great gift or “boon.” The hero must then decide whether to return to the ordinary world with this boon. If the hero does decide to return, he or she often faces challenges on the return journey. If the hero returns successfully, the boon or gift may be used to improve the world.

It’s also why Harry Potter, Star Wars, The Matrix and Star Trek are so similar. And don’t get me started on the Inheritance trilogy, whose 15-year-old author ripped off just about every famous monomyth there ever was. (via)