Castiel is a fictional character from the television series Supernatural, which aired from 2005 to 2020. He is portrayed as an angel who becomes a key ally to the show's main characters, Sam and Dean Winchester. Castiel is known for his serious demeanor, unique perspective on humanity, and his iconic trench coat. Throughout the series, Castiel struggles with his identity and the complexities of human emotions. His character evolves significantly, transitioning from a loyal servant of Heaven to a more independent figure who often questions the rules of the celestial hierarchy. Castiel's journey explores themes of friendship, sacrifice, and redemption.