Oswald Myconius (1488, Lucerne – 14 October 1552, Basel) was a follower of Huldrych Zwingli.
He was born at Lucerne, Switzerland. His family name was Geisshüsler, and his father was a miller; hence he was also called Molitoris (Latin molitor, "miller"). The name Myconius seems to have been given him by Erasmus; it is a translated Greek name from the original Swiss surname. From the school at Rottweil, on the Neckar, he went to the University of Basel to study classics. From 1514 he obtained teaching posts at Basel, where he married, and made the acquaintance of Erasmus and of Hans Holbein, the painter. In 1516 he was called, as schoolmaster, to Zürich, where (1518) he attached himself to the reforming party of Zwingli. This led to his being transferred to Lucerne, and again (1523) reinstated at Zürich.
On the death of Zwingli (1531) he moved to Basel, where he held the office of town's preacher, and (till 1541) the chair of New Testament exegesis. In confessional matters he was for a union of all Protestants; though a Zwinglian, his readiness to compromise with the advocates of consubstantiation gave him trouble with the hard-line Zwinglians. He had, however, a distinguished follower in Theodore Bibliander.
Among his several tractates, the most important is De H Zwinglii vita el obitu (1536), translated into English by Henry Bennet (1561). See Melchior Adam, Vita theologorum (1620); M Kirch-hofer, O. Myconius (1813); KR Hagenbach, J. Oekolampad und O. Myconius (1859); FM Ledderhose, in Allgemeine deutsche Biog. (1886); B Riggenbach and Egli, in Hauck's Realencyklopadie (1903).