Louis the Stammerer (November 1, 846 — April 10, 879; French: Louis le Bègue), was the eldest son of Charles the Bald and Ermentrude of Orléans. He succeeded his younger brother in Aquitaine in 866 and his father in France in 877, though he was never crowned Emperor.
Twice married, he and his first wife, Ansgarde of Burgundy, had two sons: Louis (born in 863) and Carloman (born in 866), both of whom became kings of France, and two daughters: Hildegarde (born in 864) and Gisela (865–884), who marry with Robert, Count of Troyes. With his second wife, Adelaide of Paris, he had one daughter, Ermentrude (875–914) — who was the mother of Cunigunde, wife of the Count Palatine Wigerich of Bidgau; they were the ancestors of the House of Luxemburg —, and a posthumous son, Charles the Simple, who would become, long after his elder brothers' deaths, king of France.
He was crowned on 8 December 877 by Hincmar, archbishop of Rheims, and was crowned a second time in September 878 by Pope John VIII at Troyes while the pope was attending a council there. The pope may even have offered the imperial crown, but it was declined. Louis the Stammerer was said to be physically weak and outlived his father by only two years. He had relatively little impact on politics. He was described "a simple and sweet man, a lover of peace, justice, and religion". In 878, he gave the counties of Barcelona, Gerona, and Besalú to Wilfred the Hairy. His final act was to march against the Vikings who were then the scourge of Europe. He fell ill and died on 10 April or 9 April 879 not long after beginning his final campaign. On his death, his realms were divided between his two sons, Carloman and Louis.