Gustaf V (1858 - 1950) King of Sweden. Gustaf V (Oscar Gustaf Adolf; 16 June 1858 - 29 October 1950) was King of Sweden from 1907 until his death in 1950. He was the eldest son of King Oscar II of Sweden and Sophia of Nassau, a half-sister of Adolphe, Grand Duke of Luxembourg. Reigning from the death of his father, Oscar II, in 1907 to his own death 42 years later, he holds the record of being the oldest monarch of Sweden and the third-longest rule, after Magnus IV and Carl XVI Gustaf.