Officolampadius, Or Oekojampad, Johannes, a German reformer, whose real name was IIuss-gen or Heussgen, born at Weinsberg, Swabia, in 1482, died in Basel, Nov. 23, 1531. His father was a merchant, He studied jurisprudence at Bologna and theology at Heidelberg, was tutor to the son of the elector palatine, and then held a benefice founded by his parents, but resigned both functions to continue his theological studies. He was an admirer of Erasmus, went to Basel in 1515, and assisted him in his "Annotations on the New Testament." About the end of 1518 he was invited to Augsburg. He found the city excited by a recent conference between Luther and the papal legate, and declared for the reformer. A violent dispute ensued, and he retired in 1520 to a convent of the monks of St. Bridget, near Augsburg. He stood at this time midway between Luther and Rome, desiring a "certain purified Catholicism," but was inclining more and more toward the side of the reformation. He left the convent in February, 1522, went to the castle of Ebernburg, where for a time he was preacher to Franz von Sick-ingen, and in November was at Basel, where he officiated as curate of St. Martin's. In 1523 the government council appointed him Scripture reader to the university, which refused to acknowledge him.

Still he addressed large audiences, and in 1525 was regularly appointed curate of St. Martin's. He led the discussion at the conference in Baden, in 1526, against Eck, and was distinguished there for his mildness and ability. He had written against the celibacy of the clergy, and about 1530 he married Wilibrandis, daughter of a knight of the emperor Maximilian. He supported Zwingli in his dispute with Luther respecting the real presence in the Lord's supper, and published a treatise entitled De genuina Verborum Domini, Hoc est Corpus meum, Expositions (1525) in which he maintained the word corpus to be only symbolical. He was called the Melanch-thon of Switzerland. He was a tall, handsome man, of a patriarchal presence. His widow became the wife of his friend Capito, after whose death she married Bucer. OEcolampa-dius's principal works are: Annotationes in Genesin; Exegemata in Librum Job; Com-mentariorum in Esaiam libri VI.; De Ritu Paschali; and Quod non sit onerosa Chris-tianis Confessio. His life has been written by Hess (Zurich, 1791), Herzog (Basel, 1843), and Hagenbach (Elberfeld, 1859).