Sir Gawain and the Green Knight

The story of Sir Gawain and the Green Knight is a 14th century piece of work that takes place in the time of King Arthur's Camelot. The story follows the knights of the round table on a New Year's day, when King Arthur receives a giant green knight who challenges any and all brave enough to strike him with his giant axe. No one dares accept this challenge until young Sir Gawain decides he wants to give it a try.

Gawain does so and cuts off the Green Knight's head. The knight picks up his head, puts it back on his shoulders, and tells Gawain that he is not yet done with his game. He explains that he will come back in one year and ask for Gawain's head, and whoever strikes the first blow may claim the others as forfeit.