Erik Magnusson, Duke of Södermanland

Erik Magnusson (c. 1282–1318) was the second son of King Magnus Ladulås. He was Duke of Södermanland and rival of his brother King Birger.

In 1306 he helped force the execution of Torkel Knutsson and seized Birger at the Håtuna games. In 1309 he fought the kings of Norway and Denmark, until the peace of Helsingborg divided Sweden and gave Erik several provinces.

In 1312 he married Ingeborg of Norway; their son Magnus later ruled both Sweden and Norway. At the Nyköping Banquet of 1317 Birger seized him and his brother Valdemar; both died in Nyköping Castle's dungeon, apparently starved.