Heresiarch

The noun heresiarch (also hæresiarch, according to the Oxford English Dictionary; from Greek: αἱρεσιάρχης, hairesiárkhēs via the late Latin haeresiarcha) is used to refer both to the originator of heretical doctrine, and to the founder of a sect that sustains such a doctrine. For example, according to Catholic doctrine, the founders of Protestantism, such as Martin Luther and John Calvin, were classed as heresiarchs as well as schismatics.