The lord of Otranto in Horace Walpole’s novel The Castle of Otranto is Manfred. He rules the castle and principality at the beginning of the story, but his authority is threatened by an ancient prophecy about the rightful owner reclaiming Otranto.
Manfred’s crisis begins when his son Conrad is crushed by a gigantic helmet on the day of Conrad’s wedding to Isabella. Fearing the extinction of his family line, Manfred tries to divorce his wife, Hippolita, and marry Isabella instead. His increasingly tyrannical actions drive much of the novel’s conflict.
The other answer choices are important characters, but they are not the lord. Hippolita is Manfred’s wife, Theodore becomes the true prince of Otranto, and Conrad is his son. Published in 1764, Walpole’s novel is widely regarded as the first Gothic novel and helped establish the genre’s signature blend of medieval settings, family secrets, prophecy, and supernatural events.