(formed from ὑψιστος "highest"), a sect of heretics in the fourth century; thus called from the profession they made of worshipping the most high God.

The doctrine of the Hypsistarians was 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 Hypsistari bore a near resemblance to the Euclites, or Massilians.