King Magnus III of Sweden, in Swedish "Magnus Ladulås", was at times in error called "Magnus I".

Magnus I ( ; ) (born about 1106, died 4 June 1134 in the Battle of Fotevik), was a Danish duke who ruled Gothenland in southern Sweden from 1125 to 1130. His status as ruler of Sweden was disputed in his own time, but today he is recognized as one of the historical Swedish monarchs. Snorri Sturlason invented an epithet for him: Magnus the Strong.