A younger son of House Hightower of Oldtown who rose to become Hand of the King to two Targaryen monarchs. Old King Jaehaerys I named him to the office in his last years, and when Viserys I came to the throne Ser Otto kept his white rod, brought his young daughter Alicent to court to attend the ailing king, and made of her in time a queen. His feud with Prince Daemon Targaryen (whom he distrusted as ruinous and ambitious) and his quiet championing of Alicent's children over Princess Rhaenyra split the realm at court long before it split in arms, and he was twice removed from the Handship by Viserys for pressing the matter too hard.
When King Viserys died in 129 AC, Ser Otto stood at the heart of the green council that crowned his grandson Aegon II in the Dragonpit and set aside the king's named heir. He served his grandson as Hand through the opening campaigns of the Dance of the Dragons, until quarrels over the prosecution of the war saw him dismissed in favor of Ser Criston Cole. After Rhaenyra took King's Landing he was taken and put to the sword on her order, his head set above the gates of the city he had ruled in his grandson's name.