The Knight of the Mirrors, also known as Samson Carrasco, is a character in 'Don Quixote' who embodies the duality of reality and illusion. He serves as an antagonist to Don Quixote, attempting to confront and ultimately bring him back to sanity by challenging his delusions of chivalry. Carrasco’s role illustrates the complexities of perception and the often blurry line between fantasy and reality in the narrative.