Haakon VI Magnusson (Håkan Magnusson) (appr. 1340 – 1380), was King of Norway 1343-80 and co-king of Sweden 1362-64.
He was the younger son of King Magnus Eriksson of Sweden and Norway and Blanche of Namur. In 1343 he succeeded his father to the Norwegian throne, who would still rule during his minority, until 1355 when he reached majority as sovereign of Norway.
15 February 1362 he was elected (co)king of Sweden in Mora stones (representatives of Finland taking part in the election for the first time) at instigation of nobles, but soon in agreement with his father. In 1363 he married Margaret of Denmark, daughter of King Valdemar IV of Denmark. In 1370 they had the son Olav who would succeed his grandfather to the Danish throne in 1376.
His cousin Albert III of Mecklenburg and nobles moved against his father in Sweden, ultimately deposing Haakon and Magnus and taking the old king prisoner.
Haakon then concentrated mainly on business of his Norwegian kingdom. However he succeeded in getting his father released and allowed to settle in Norway where he died. Some occurrences, they made efforts to oust Albert. Haakon continued to claim the Swedish throne, a reason why his wife and later widow Margaret used the title queen of Sweden until her own death.
In 1379 Haakon solved the disputes over succession in the Norse earldom of Orkney, awarding it to Henry Sinclair, ocean explorer, a (youngest) grandson of earl Maol Iosa, over the widower of Maol Iosa's elder daughter and other descendants.