(formed from ὑψος, highest), a sect of heretics in the fourth century, who were so called from the profession they made of worshipping the Most High God.

The doctrine of the Hypsistarians may be considered as an assemblage of Paganism, Judaism, and Christianity. They adored the Most High God with the Christians; but they also revered fire and lamps with the heathens, and observed the sabbath, and the distinction of clean and unclean things with the Jews.

The Hypsistarii bore a near resemblance to the Euclites, or Massalians.