Sigebert III was the Merovingian king of Austrasia from 633 to his death around 656. He was described as the first Merovingian roi fainéant, or "do-nothing king", with the mayor of the palace in fact ruling the kingdom throughout his reign. Nevertheless, Sigebert lived a pious Christian life and was later sanctified, being remembered as Saint Sigebert of Austrasia in the Roman Catholic Church and Eastern Orthodox Church.