In Horace Walpole’s *The Castle of Otranto*, the peasant who becomes the rightful heir is Theodore.
Theodore first seems to be a minor peasant who helps Isabella escape after Conrad is crushed by the gigantic helmet. His knowledge of the strange object draws Manfred’s suspicion, and Theodore is imprisoned and condemned. His apparent low social status is part of the novel’s larger mystery about identity and inheritance.
During Theodore’s attempted execution, Friar Jerome recognizes a birthmark and realizes that Theodore is his lost son. The discovery proves that Theodore is of noble birth. Later, the supernatural history of Otranto establishes that he is descended from Alfonso, the castle’s legitimate former prince.
The revelation fulfills the prophecy that Otranto will pass from Manfred’s family when its true owner becomes able to claim it. After Matilda’s accidental death and Manfred’s repentance, Theodore becomes prince of the castle’s remains and marries Isabella. Frederic is a claimant connected to Isabella, while Conrad is Manfred’s dead son; neither is the rightful heir.