Arnulf of Carinthia
Louis was born in September or October 893 in Altötting, Duchy of Bavaria. He was the only legitimate son of king Arnulf of Carinthia and his wife, Ota, a member of the Conradine dynasty. He had at least two brothers: his elder, illegitimate brother Zwentibold, who ruled Lotharingia, and another brother named Ratold, who briefly ruled Kingdom of Italy. Ratold's maternity and age are unknown.