Childebert III the Adopted (Childebertus Adoptivus) was a Frankish king. Childebert was a son of the Mayor of the Palace Grimoald the Elder. He was thus a grandson of Pepin of Landen. He was adopted by King Sigebert III and Queen Chimnechild. When Sigebert III died in 656, Grimoald had Sigebert’s biological son Dagobert II tonsured and sent him to an Irish monastery and then proclaimed Childebert king of Austrasia. The family reappeared in politics with the rise of Ansegisel’s son, Pepin of Herstal.