Norway stamp Michel no. 4, issued in 1856, depicting king Oscar I.

Oscar I, born Joseph François Oscar Bernadotte (1799–1859), was King of Sweden and Norway from 1844 to his death. He was the only son of Charles XIV John of Sweden and his wife, Queen Desideria. When, in August 1810, Bernadotte was elected Crown Prince of Sweden, Oscar and his mother removed from Paris to Stockholm.

From Charles XIII of Sweden the lad received the title of Duke of Sudermannia. He quickly acquired the Swedish language, and, by the time he reached the age of majority, had become a general favourite. Twice during his father's lifetime he was viceroy of Norway. On June 19, 1823 he married the princess Josephine.

Oscar was crowned on March 8, 1844. He would not hear of any radical reform of the cumbrous and obsolete Constitution of 1809. But one of his earliest measures was to establish freedom of the press. He formally established equality between his two kingdoms by introducing new flags with a common union badge and a new coat of arms for the union. Most of the legislation during Oscar I's reign aimed at improving the economic position of Sweden.

In foreign affairs Oscar I was a friend of the principle of nationality. In 1848 he supported Denmark against Prussia in the First War of Schleswig. He was also one of the guarantors of the integrity of Denmark. As early as 1850 Oscar I had conceived the plan of a dynastic union of the three Scandinavian kingdoms, but such difficulties presented themselves that the scheme had to be abandoned.

Oscar I left four legitimate sons, of whom two, Carl and Oscar, succeeded him to the throne.