Monothelitism and Monothelites
A modification of Monophysitism proposing that Christ had no human free will. Rejected by the Third Council of Constantinople (680).
http://www.newadvent.org/cathen/10502a.htm

Arianism [Catholic Encyclopedia]
Founded by Arius, belief asserting that Christ was not God like the Father, but a creature made in time. Rejected by the Council of Constantinople (381).
http://www.newadvent.org/cathen/01707c.htm

Adoptionism [Catholic Encyclopedia]
The theory that the man Jesus at some point in time became the Son of God only by adoption. Strictly speaking, refers to an eighth-century Spanish heresy, but the term is also used to cover similar beliefs.
http://www.newadvent.org/cathen/01150a.htm

Docetae [Catholic Encyclopedia]
Docetism, from the Greek "dokeo" (to seem, to appear) was the contention that Christ merely seemed to be human and only appeared to be born, to suffer, and to die. Already in New Testament times, the Gospel of John opposes Docetism, and so do Ignatius, Irenaeus, and other Fathers.
http://www.newadvent.org/cathen/05070c.htm

Nestorianism [Catholic Encyclopedia]
Belief attributed to Nestorius that Christ's two natures reflect two persons, and denying of the Virgin Birth. Rejected by the Council of Ephesus (431).
http://www.newadvent.org/cathen/10755a.htm

Pelagianism [Catholic Encyclopedia]
Belief founded by Pelagius that denied original sin as well as Christian grace. Rejected by the Council of Carthage (481)
http://www.newadvent.org/cathen/11604a.htm

Monophysites and Monophysitism [Catholic Encyclopedia]
Rejected the dual nature of Christ. Rejected by the Council of Chalcedon (451).
http://www.newadvent.org/cathen/10489b.htm

Ebionites [Catholic Encyclopedia]
Two varieties: the earlier group called Ebionites denied the divinity of Christ; the later Ebionites were a Gnostic sect who believed that matter was eternal and was God's body.
http://www.newadvent.org/cathen/05242c.htm

Monarchians [Catholic Encyclopedia]
The so-called Dynamic Monarchians were actually a form of adoptionism. Monarchianism, properly speaking, refers to the Modalists. Denial of the Trinity, assertion that there is only one Divine Person, who appears in three different roles. Noetians and Sabellians were two schools of Modalism.
http://www.newadvent.org/cathen/10448a.htm

Marcionites [Catholic Encyclopedia]
Said that the creator "god" of the Old Testament was not the good God and Father of Jesus Christ of the New Testament. Had their own shadow hierarchy and their own Bible, which consisted of parts of Luke and Paul, edited so as to disparage the Old Testament. Only the unmarried were allowed to be baptized. Marcionism may have led to the formation of the Apostle's Creed as rebuttal, and certainly was an incentive in deciding on the canon of the New Testament.
http://www.newadvent.org/cathen/09645c.htm

Heresies, Authority, Quarrels and Words
An account and analysis of belief systems declared heretical by the Catholic Church. Site is sharply critical of authority and religion, and especially of the Church.
http://www.abelard.org/heresies/heresies.htm

Assyrian Church of the East
Includes ancient and modern documents.
http://www.nestorian.org