who executed otto hightower in the books

Otto Hightower is not shown as being personally executed by a named person in the book. In Fire & Blood, he is simply described as the first traitor to be beheaded when Rhaenyra takes King’s Landing, so the text leaves the actual executioner unspecified.

Book version

• The book says Otto was the first to be beheaded after Rhaenyra’s return to power.

• It does not clearly state that Rhaenyra herself swung the sword.

• That makes the executioner in the books effectively anonymous, likely a formal executioner rather than a specific character.

Show vs. book

• The show gives the death directly to Rhaenyra.

• The book is vaguer and only confirms that Otto was executed for treason.

Quick answer

No one named is identified in the books as the one who executed Otto Hightower; Fire & Blood only says he was beheaded as one of Rhaenyra’s traitors.