CJ and Harriet Hook. He is the first mate of Uma's pirate crew. Harry is Uma's oldest, and closest, friend. Having been described as defending Uma from bullying and harrassment.
Harry is sneaky, wild, unpredictable (which can be perceived as crazy), rude, evil but has a heart. His Heart is shown (figuratively) when it comes to his hook. Harry is fond of his hook to the point of being obsessed with it. When Jay grabbed his hook and threatened to drop it into the ocean, Harry backed away and dropped his sword like people would do in a hostage situation. When Jay dropped it into the ocean, Harry jumped in after it without a second thought. The hook may be a memory or deep connection to his father, Captain Hook.
- Harry initially had a hard time accepting he was not the captain of the pirate crew, but by the time of Descendants 2, he shows an unquestionable loyalty to Uma and knows what she wants done. As her first mate, he follows her orders without any hesitation or complaint; as shown in What's My Name?, Harry even makes sure the rest of the crew knows to respect and obey Uma.
- Gil was seen kissing Harry Hook,  however, it was never scripted or directed and was an improvised scene between the two actors.  But it was mentioned in the novelization of the film Rise of the Isle of the Lost: A Descendants Novel.
- He is punctual (despite not knowing how to read a watch) and has a very violent imagination.
- He carries around a hook, resembling the one his father wore. However, he himself has two hands.
- In Rise of the Isle of the Lost: A Descendants Novel, some details about Harry are revealed:
- He is the second child of Captain Hook, while Harriet is the eldest and CJ is the youngest.
- He was the first one to join Uma's pirate crew.
- He once tried to entice Tick-Tock the Crocodile to bite his hand so that he could wear a real hook like his father, but the crocodile just opened one eye and went back to sleep.
- According to Dove Cameron she and Thomas, drew hooks on their wrists every day during filming.