Oxenstiern (Swed. Oxenstjerna), Axel, count, a Swedish statesman, born at Fanö, in Upland, June 16,1583, died in Stockholm, Aug. 28, 1654. He studied at the universities of Rostock, "Wittenberg, and Jena, and visited most of the German courts. In 1606 he was sent on a mission to Mecklenburg; in 1608 he was made a member of the senate; and when Charles IX. became incapacitated, he was chosen president of the council of regency. On the accession of Gustavus Adolphus in 1611 he was appointed chancellor, concluded a peace between Denmark and Sweden in 1613, accompanied the king to Livonia in his campaigns against the Russians, and in 1617 negotiated the treaty of Stolbova, by which Sweden gained a large territory along the Baltic. During the following years he was engaged in warlike operations or negotiations connected with the thirty years' war, and in 1629, through the mediation of France and England, concluded an armistice for six years between Sweden and Poland. He accompanied Gustavus Adolphus in his German campaign, and on the death of the king at Lützen in 1632 assumed the task of continuing the war.
He was invested with full powers by the Swedish Bilctdag, and elected by the German Protestant assembly of Heilbronn chief of the league against Austria. It was not until everything had been placed on a safe footing in Germany that he returned to Sweden, to resume his duties as chancellor, and act as one of the guardians of the young queen Christina, he being the actual ruler of Sweden during her minority. He improved the finances, encouraged trade, and patronized learning; and when the sovereign became of age in 1644 the kingdom was in a most prosperous condition. After that the intrigues of the courtiers gradually undermined his influence. Oxenstiern was an accomplished scholar, and some of his writings, including his correspondence with his son during the negotiation which preceded the peace of Westphalia, have been printed. The second volume of the Historia Belli Suevo-Gcrmanici, the first of which is from the pen of Chemnitz, is ascribed to him.