Johannes Oecolampadius, , or Oekolampad (1482 – 24 November 1531) was a German theologian religious reformer from the Electorate of the Palatinate. He worked with Erasmus and Zwingli, and also influenced a later generation of Protestants, including Heinrich Bullinger and John Calvin. Theologically he was considered to be close to Zwingli, with whom he shared a friendly attitude towards Mary and Marian veneration.