Magnus II of Sweden (1240 – 1290), often called Ladulås: Barnlock, was king of Sweden from 1275/1280 until his death in 1290. Later historians ascribe his epithet to a decree of 1279 freeing the Yeomanry from the duty to provide sustenance for travelling Nobles and Bishops ("Peasants! Lock your barns!), but probably its simply a corruption of Ladislaus.

With the Alsnö stadga about 1279, Magnus III gave anyone who supported the Crown with a knight and a horse freedom from certain taxes (such a freedom was called frälse in Swedish. This is often (mistakenly) said to be the formal foundation of the Swedish nobility.

Son to Birger Jarl (Earl Birger Magnusson) and Ingeborg Eriksdotter of Sweden . Magnus Ladulås married 1276 as his second wife Helvig of Holstein , daughter of Gerhard I of Holstein and Queen Regent (probably 1290-1302 and) 1320-1327. A papal anullment of his first marriage and a dispensation for his second (consanguinuity) were issued ten years later, in 1286.

Children of his second marriage to Helvig of Holstein

1. Ingeborg Magnusdotter of Sweden, born abt. 1279. Married King Erik Menved of Denmark.
2. Birger Magnusson of Sweden, born abt. 1280 king of Sweden.
3. Eric Magnusson of Sweden , Duke of Södermanland in 1302, born abt. 1282. Died of starvation 1318 at Nyköpingshus castle while imprisoned by his brother King Birger.
4. Valdemar Magnusson, Duke of Finland in 1302 and Öland 1310. Died of starvation 1318 at Nyköpingshus castle while imprisoned by his brother King Birger.
5. Rikissa Magnusdotter, abbess of the convent of Sta Clara at Stockholm. Died after 1347.