Sir Gawain and the Green Knight
Sir Gawain and the Green Knight is a Medieval English romance about Sir Gawain, one of King Arthur's Knights. It was written in the late fourteenth century and is set somewhere around the sixth century. The author is called the "Pearl Poet". Nothing conclusive is known about his identity. The first modern edition was published by J.R.R. Tolkien and E. V. Gordon in 1925.
One of Sir Gawain and the Green Knight's themes is the fine line between chivalry and Christian virtues.
An excellent free translation:.