Theuderic III was a king of the Franks who ruled from 673 to 691 AD. He was a member of the Merovingian dynasty, which was known for its long line of kings in what is now modern-day France. His reign was marked by internal conflicts and power struggles, particularly with his half-brother, Clovis IV, and other noble families. During Theuderic III's rule, the authority of the Merovingians began to decline, leading to the rise of the mayors of the palace, who effectively held power behind the throne. Theuderic III's reign ended when he was deposed, and he was succeeded by Childebert III, further signaling the weakening of the Merovingian rule.