Oscar II (Oscar Fredrik; 21 January 1829 – 8 December 1907) was the King of Sweden from 1872 until his death, and was also the final King of Norway from the House of Bernadotte until being deposed in 1905.

Oscar II was King during a time when both Sweden and Norway were undergoing a period of industrialization and rapid technological progress. His reign also saw the gradual decline of the Union of Sweden and Norway, which culminated in its dissolution in 1905. He was subsequently succeeded as King of Norway by his grandnephew Prince Carl of Denmark under the regnal name Haakon VII, and as King of Sweden after his death in 1907 by his eldest son, Gustaf V.

Oscar II became King on 18 September 1872, upon the death of his brother, Charles XV. At his accession, he adopted as his motto “Brödrafolkens väl / Broderfolkenes Vel” ("The Welfare of the Brother Peoples"). Oscar II made the effort of learning to be fluent in Norwegian, however he realized from the very beginning the essential difficulties in the maintenance of the union between the two countries.