Zwentibold (870 - August 13, 900) was the illegimate son of the Emperor Arnulf of Carinthia. In 895 his father granted him the Kingdom of Lotharingia, which he ruled until his death.
He had great problems controlling the nobility. In 899 Arnulf died and his legitimate son Louis the Child became German king. Zwentibold attempted to take advantage of the succession of his young half-brother to establish complete independence for his kingdom. However, the nobility supported Louis and asked him to intervene. In 900, Reginar (also known as Rainier), count of Hainaut rose against Zwentibold and slew him near present-day Susteren.
After Zwentibold’s death, his half-brother Louis the Child also became king of Lotharingia, but the realm was administered by a duke, since 904 by the Conradine Gebhard of Franconia.