Louis the Child, sometimes called Louis III or Louis IV, was the king of East Francia from 899 until his death and was also recognized as king of Lotharingia after 900. He was the last East Frankish ruler of the Carolingian dynasty. He succeeded his father, Arnulf, in East Francia and his elder illegitimate half-brother Zwentibold in Lotharingia.

East Francia or the Kingdom of the East Franks was a successor state of Charlemagne's empire ruled by the Carolingian dynasty until 911. It was created through the Treaty of Verdun (843) which divided the former empire into three kingdoms.