A heresiarch is a founder or leader of a heretical

Heresy

Heresy is a controversial or novel change to a system of beliefs, especially a religion, that conflicts with established dogma. It is distinct from apostasy, which is the formal denunciation of one's religion, principles or cause, and blasphemy, which is irreverence toward religion...

 doctrine

Doctrine

Doctrine is a codification of beliefs or a body of teachings or instructions, taught principles or positions, as the body of teachings in a branch of knowledge or belief system...

 or movement

Cultural movement

A cultural movement is a change in the way a number of different disciplines approach their work. This embodies all art forms, the sciences, and philosophies. Historically, different nations or regions of the world have gone through their own independent sequence of movements in culture, but as...

, as considered by those who claim to maintain an orthodox

Orthodoxy

The word orthodox, from Greek orthos + doxa , is generally used to mean the adherence to accepted norms, more specifically to creeds, especially in religion...

 religious tradition or doctrine. For example, according to traditional Catholic

Catholic

The word catholic comes from the Greek phrase , meaning "on the whole," "according to the whole" or "in general", and is a combination of the Greek words meaning "about" and meaning "whole"...

 doctrine, the protestant reformers such as Martin Luther

Martin Luther

Martin Luther was a German priest, professor of theology and iconic figure of the Protestant Reformation. He strongly disputed the claim that freedom from God's punishment for sin could be purchased with money. He confronted indulgence salesman Johann Tetzel with his Ninety-Five Theses in 1517...

 and John Calvin

John Calvin

John Calvin was an influential French theologian and pastor during the Protestant Reformation. He was a principal figure in the development of the system of Christian theology later called Calvinism. Originally trained as a humanist lawyer, he broke from the Roman Catholic Church around 1530...

 were heresiarchs. The miller Domenicio Scandella (called Menocchio

Menocchio

Menocchio, also known as Domenico Scandella, was a Friulian miller born in 1532 in the village of Montereale, twenty-five kilometers north of Pordenone...

) of Carlo Ginzburg

Carlo Ginzburg

Carlo Ginzburg is a noted historian and proponent of the field of microhistory. He is best known for his Il formaggio e I vermi which examined the beliefs of an Italian heretic, Menocchio, from Montereale Valcellina.- Biography :The son of Natalia Ginzburg and Leone Ginzburg, he was born...

's The Cheese and the Worms was also declared a heresiarch by the Inquisition judges.

The first official heresy of the Christian church, Arianism

Arianism

Arianism is the theological teaching attributed to Arius , a Christian presbyter from Alexandria, Egypt, concerning the relationship of the entities of the Trinity and the precise nature of the Son of God as being a subordinate entity to God the Father...

, was created by heresiarch Arius

Arius

Arius was a Christian presbyter in Alexandria, Egypt of Libyan origins. His teachings about the nature of the Godhead, which emphasized the Father's divinity over the Son , and his opposition to the Athanasian or Trinitarian Christology, made him a controversial figure in the First Council of...

. It taught that Jesus was of lesser being than God, and was rebuked by Constantine's First Ecumenical Council of Nicea, which asserted that Jesus and God the Father were "consubstantial

Consubstantiality

Consubstantial is an adjective used in Latin Christian christology, coined by Tertullian in Against Hermogenes 44, used to translate the Greek term homoousios...

", i.e. of the same divine being.