Manfred, Prince of Otranto – an arrogant, unprincipled man who lives in the shadow of a curse
Hippolita, the wife of Manfred – a noble, virtuous and religious woman who loves her husband, although he does not deserve her love
Manfred becomes obsessed with finding and marrying Isabella. But, first, he must divorce Hippolita. She is a devout woman who will do as a priest asks her, so Manfred wants the priest, Jerome, to convince her to accept the divorce. Since Isabella has asked for shelter in the church until her father arrives, Jerome is well-aware of Manfred’s ill intent toward her. There is some confusion here – some believe the father is dead, but she believes he is alive.
Conrad – the son of Manfred and Hippolita, who dies at age 15
Matilda – the beautiful, sweet daughter of Manfred and Hippolita, who is 18
She is thegood daughter of Manfred, is intrigued by the portrait of the young Alfonso the Good that hangs in her castle. It is clear that she longs for someone like Alfonso in her life. She begins to get to know Theodore when he is imprisoned and realizes that he is a man of quality.
Matilda has never been close to her father and is trying to figure out why he is so intent on bringing Isabella back to the castle. When all of the men leave the castle to find Isabella, Matilda frees Theodore and insists that he leaves the castle to save his life. She has noticed that Theodore resembles the picture of the former prince, Alfonso, and she falls in love with him.
Isabella – the fiancée of Conrad and daughter of Frederic
Frederic – Marquis of Vicenza, who is the father of Isabella
Jerome – Count of Falconara, who now lives as a friar
Theodore Falconara – son of Jerome, who grew up as a peasant
As Manfred and Jerome meet, Manfred decides to execute Theodore, who has proven to be articulate, wise, and resourceful. Just as Theodore is about to be executed, Jerome realizes that Theodore is his son, an awkward thing for a priest to admit. Jerome admits he was the former Count of Falconara who lost his estate, wife, and son due to an enemy attack.
Manfred, though generally evil, seems to have some decency and spares the boy. Theodore is mysteriously in love with Matilda, even before he meets her. In fact, he thinks it is Matilda he is helping when he assists Isabella in escaping. Theodore is knightly, almost worshipping the women in his life and vowing to protect them.
Bianca – servant of Matilda
Frederic, the Marquis of Vincenza
Before Manfred can find Isabella and force her to marry him, a huge entourage of knights and courtiers arrive in search of Isabella. One of the knights, unbeknownst to Manfred, is Frederic, Isabella’s father. When Theodore escapes the castle, he goes to a wood, and finds a cave. He accidentally meets up with Isabella and vows to protect her. In the meantime, all of Manfred’s men and Vincenza, as well, are looking for Isabella. Vincenza finds the cave, and Theodore fights with him, nearly mortally wounding the man, without realizing that Vincenza is Isabella’s father.
Manfred — the lord of the Castle of Otranto. He is the father of Conrad and Matilda, and the husband of Hippolita. After his son is killed by the falling helmet, he becomes obsessed with the idea of ending his marriage with Hippolita in pursuit of the much younger Isabella, who was supposed to marry his son. Manfred serves as the prime antagonist of the novel; he is the dictatorial ruler and father that drives the plot forward in a depiction of deranged cruelty visited upon his children.
Hippolita — the wife of Manfred and the mother of Conrad and Matilda. After having lost her son, she is left with just Matilda to combat the tyrannical turn of mind that her husband displays. Manfred intends to divorce her due to her sterility and on the grounds that their marriage is in fact false because they are actually related. Faced with the threat of divorce, Hippolita is mournful yet submissive to the wills of her husband. She acts as a sort of enabler to her husband, putting aside her morals and happiness so that her husband can get what he wants.
Conrad — the fifteen-year-old son of Manfred and Hippolita and the younger brother of Matilda. In the first pages of the novel, he is crushed by a giant helmet on his way to his wedding with Isabella.
Matilda — Matilda is the daughter of Hippolita and the oppressive Manfred. She falls in love with Theodore, much to her chagrin since it is a love unsanctioned by her parents. Upon the appearance of Frederic, things become even more complicated as Frederic lusts after Matilda. She serves as the forbidden woman, a facet of Gothic literature. Frederic and Manfred make plans to swap their daughters in marriage, crushing Matilda’s hope of being with Theodore. At the end of the novel, she is mistakenly stabbed by her father.
Isabella — the daughter of Frederic and the fiancée of Conrad (at the beginning of the novel). After the death of Conrad, she makes it clear that, although she did not love Conrad, she would have far preferred being betrothed to him rather than his father, who pursues her throughout the novel. Isabella and Matilda have a brief argument concerning the fact they both have feelings for Theodore. After the death of Matilda, Theodore settles for Isabella and the two become the lord and lady of the castle.
Theodore — at the beginning of the novel, Theodore appears to be a mere minor character, whose role is purely to point out the significance of the helmet as a link to the fulfilment of the prophecy. However, he emerges as a main character after Manfred orders him to be imprisoned within the helmet for his insolence and he escapes, only to help Isabella escape from the castle through a trapdoor. He is revealed later in the novel to be the lost son of Friar Jerome. Theodore proceeds to protect Isabella from the wanton lust of Manfred. He captures the hearts of both Isabella and Matilda, but settles for Isabella after Matilda’s death. He also later goes on to rule the Castle of Otranto.
Friar Jerome — the friar at the monastery near the Castle of Otranto. Manfred attempts to manipulate him into both supporting his plan to divorce his wife and persuading his wife to go along with this plan. It is later discovered that he is Theodore’s father.
Frederic — the long-lost father of Isabella who appears late into the novel. He opposes Manfred at first, until he settles on a deal to marry Matilda.
Bianca — the servant of Matilda who serves as a comic relief of the otherwise highly melodramatic novel.
Diego and Jaquez — these two, like Bianca, are other servants within the Castle of Otranto.