John I, Duke of Saxony

John I (1249–1285) was Duke of Saxony from the House of Ascania. After his father Albert I died in 1260, he ruled jointly with his younger brother Albert II, gradually partitioning the three disconnected Saxon lands between them in 1269, 1272 and 1282.

In 1270 he married Ingeborg. In 1282 he resigned in favour of his three minor sons John II, Eric I and Albert III, and entered the Franciscan monastery at Wittenberg, where he died on 30 July 1285.