Bertilak de Hautdesert is a character from the medieval poem Sir Gawain and the Green Knight. He is the lord of a castle where Sir Gawain stays during his quest. Bertilak is known for his hospitality and generosity, welcoming Gawain and offering him food and shelter. Bertilak is also significant for his role in the poem's themes of honor and temptation. He challenges Gawain to a game that tests the knight's integrity. Ultimately, Bertilak's true identity is revealed to be connected to the Green Knight, adding depth to the story's exploration of chivalry and moral values.