Derfel Cadarn is a fictional character from the historical fantasy series "The Warlord Chronicles" by Bernard Cornwell. He is depicted as a warrior and a loyal follower of King Arthur, navigating the tumultuous landscape of post-Roman Britain. Derfel's character is known for his bravery, intelligence, and moral complexity. In the series, Derfel serves as a narrator, providing insights into the events and characters around him. His journey intertwines with legendary figures such as Merlin and Guinevere, exploring themes of loyalty, honor, and the struggle between paganism and Christianity in a changing world.