John Chryssavgis (born 1 April 1958) is an Orthodox Christian theologian who serves as advisor to the Ecumenical Patriarch on environmental issues. He is a clergyman of the Greek Orthodox Archdiocese of America. In January 2012, he received the title of Archdeacon of the Ecumenical Throne by His All-Holiness Ecumenical Patriarch Bartholomew. In 2016, he was awarded an honorary doctorate by St. Vladimir’s Theological Seminary. In 2020, he was elected Honorary Professor of Theology in the Sydney College of Divinity.