Louis III, c.863–882, French king, son of King Louis II. He became joint ruler with his brother Carloman on the death of Louis II (879), despite the attempts of Louis the Younger to become French king. Louis III and Carloman fought against the secessionists of Burgundy and Provence and resisted an invasion of the Normans, whom Louis routed (881) at Saucourt. His death left Carloman sole ruler.

Louis III, 1403–34, king of Naples (1417–34; rival claimant to Joanna II), duke of Anjou, count of Provence, son and successor of Louis II. He invaded Naples in 1420. Queen Joanna called in the aid of Alfonso V of Aragón and Sicily and adopted him as heir (1421), but Alfonso's domineering attitude caused her (1423) to adopt Louis instead. Louis had gained control of most of the kingdom when he died. Joanna made his brother René heir.

Louis III, 1845–1921, last king of Bavaria (1913–18). He succeeded (1912) his father, Luitpold, as regent for the insane Otto I but proclaimed himself king in 1913. He was overthrown in the Bavarian revolution of Nov., 1918.