ECKIUS or ECHUS, JOANNES (1483–1543), the antagonist of Luther, was born in Suabia. His family name was Mayer. He was professor at Ingolstadt, and at the Reformation disputed both with Luther and Carlstadt. At the diet of Augsburg he argued against the Protestant Confession. He wrote a work entitled Enchiridion Controversiarum; Apologia contra Bucerum; a tract on the Mass; an Exposition of Haggai; and several smaller works.