Born abt 1106. Parents: King Nils of Denmark and Margareta Fredkulla, daughter of Inge the older.
Elected King abt 1125. Deposed in 1130. He died in the battle of Fotevik in Scania 4 of June 1134.
Married to Rikissa (1106-1156), daughter of King Boleslav III of Poland. After Magnus' death she was married to a Russian prince and to King Sverker I.
Son: Knut, King of Denmark (died 1157).