Louis IV, called d'Outremer or Transmarinus, reigned as King of West Francia from 936 to 954. A member of the Carolingian dynasty, he was the only son of king Charles the Simple and his second wife Eadgifu of Wessex, daughter of King Edward the Elder of Wessex. His reign is mostly known thanks to the Annals of Flodoard and the later Historiae of Richerus.

In medieval historiography, West Francia or the Kingdom of the West Franks constitutes the initial stage of the Kingdom of France and extends from the year 843, from the Treaty of Verdun, to 987, the beginning of the Capetian dynasty. It was created from the division of the Carolingian Empire following the death of Louis the Pious, with its neighbor East Francia eventually evolving into the Kingdom of Germany.