Johannes Oecolampadius, or Oekolampad (1482 – November 24, 1531) is a German theologian religious reformer from the Electorate of the Palatinate.

He works with Erasmus and Zwingli; he also influences a later generation of Protestants, including Heinrich Bullinger and John Calvin.

Theologically he is considered to be close to Zwingli, with whom he shares a friendly attitude towards Mary and Marian veneration.

His real name is Hussgen or Heussgen, a name first changed to Hausschein and then into the Greek equivalent, which is derived from οίκο- oiko-, "house," and λαμπάδ- lampad-, "lamp".