Oscar II (baptised Oscar Fredrik; 21 January 1829 – 8 December 1907) was King of Sweden from 1872 until his death and King of Norway from 1872 until his dethronement in 1905.

He was the third of four sons of King Oscar I and Josephine of Leuchtenberg and was given the title of Duke of Östergötland. As his eldest brother Charles XV was without heirs (his only son having died in infancy in 1854) and his brother Prince Gustaf died in 1852, it was he who succeeded his brother as king.

Oscar II was king during a period when Sweden was undergoing a period of industrialization and rapid technological progress. The declining Union of Sweden and Norway was finally dissolved in 1905 and Oscar became the last Bernadotte king of Norway. He died in 1907 and was succeed as King of Sweden by his son, Gustaf V.

At his birth in , Oscar Fredrik was created Duke of Östergötland. He entered the navy at the age of eleven, and was appointed junior lieutenant in July 1845. Later he studied at Uppsala University, where he distinguished himself in mathematics. On 13 December 1848, he was made an honorary member of the Royal Swedish Academy of Sciences.

On 6 June 1857 he married in Wiesbaden-Biebrich, Germany, Princess Sophia Wilhelmina, youngest daughter of Duke William of Nassau.

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