Mar Shimun XVI Yohannan (also Shemon XVI Yohannan) was Patriarch of the Shem'on line (Qodshanis) of the Church of the East, from 1780. In 1804, he became the sole Patriarch among traditionalist Christians of the East Syriac Rite, because the rival Patriarch Eliya XII (1778-1804) of the Eliya line died without successor. Shimun XVI remained patriarch until his death in 1820.