Rassendyll is the main character in the novel "The Prisoner of Zenda," written by Anthony Hope. He is an Englishman who bears a striking resemblance to the imprisoned King Rudolf V of Ruritania. This resemblance leads Rassendyll to become involved in a political plot to save the king and restore him to the throne. Throughout the story, Rassendyll displays bravery and resourcefulness as he navigates the dangers of court intrigue and betrayal. His adventures highlight themes of identity, duty, and the clash between personal desires and responsibilities to others.