Old Calendarists

Old Calendarists (Greek: palaioimerologitai or palaioimerologites), also known as Old Feasters (palaioeortologitai), Genuine Orthodox Christians or True Orthodox Christians (GOC; Greek: Γνήσιοι Ορθόδοξοι Χριστιανοί, romanized: Gnisioi Orthodoxoi Christianoi), are traditionalist groups of Eastern Orthodox Christians that separated from mainstream Eastern Orthodox churches because some of the latter adopted the revised Julian calendar while Old Calendarists remained committed to the Julian calendar.

Old Calendarists are not in communion with any mainstream Eastern Orthodox churches.

"Old Calendarists" is another name for the True Orthodox movement in Romania, Bulgaria, Greece and Cyprus.