Carloman II (c. 866 – 12 December 884) was the King of West Francia from 879 until his death. A member of the Carolingian dynasty, he and his elder brother, Louis III, divided the kingdom between themselves and ruled jointly until the latter's death in 882. Thereafter Carloman ruled alone until his own death. He was the second son of King Louis the Stammerer and Queen Ansgarde.
Upon Louis the Stammerer's death, some Frankish nobles advocated electing Louis III as the sole king, but eventually both brothers were elected kings. Carloman was crowned in September 879 at Ferrières-en-Gâtinais. Although some doubts were cast upon the legitimacy of their birth, the brothers obtained recognition and in March 880 divided their father's realm at Amiens, Carloman receiving southern Kingdom of Burgundy and Kingdom of Aquitaine.
Meanwhile, the powerful Duke Boso of Provence had renounced his allegiance to both brothers and had been elected King of Provence. In the summer of 880 Carloman and Louis III marched against Boso, took Mâcon and the northern parts of his realm. Despite receiving help from their cousin Charles the Fat, who ruled East Francia and Kingdom of Italy the siege of Vienne lasted from August to November without success. Only in the summer of 882 Vienne was taken after being besieged by Richard, Count of Autun.
After the accidental death of Louis III in August 882, Carloman II became the sole king of West Francia. The kingdom was in a deplorable condition partly owing to repeated incursions from the Viking raiders, and his power was very limited by rebellious nobles, especially in Burgundy.
Carloman II died near Les Andelys while hunting on 12 December 884 and was succeeded in the throne by his cousin, the Emperor Charles the Fat. He is buried in the Saint Denis Basilica in Paris.