The Athanasian Creed, also called the Pseudo-Athanasian Creed and sometimes known as Quicunque Vult (or Quicumque Vult), which is both its Latin name and its opening words, meaning "Whosoever wishes", is a Christian statement of belief focused on Trinitarian doctrine and Christology. Used by Christian churches since the sixth century, it was the first creed to explicitly state the equality of the three hypostases of the Trinity. It differs from the Nicene-Constantinopolitan Creed and the Apostles' Creed in that it includes anathemas condemning those who disagree with its statements (as does the original Nicene Creed).

Widely accepted in Western Christianity, including by the Roman Catholic Church, some Anglican and Lutheran churches (it is part of the Lutheran confessions set out in the Book of Concord), and ancient liturgical churches, the Athanasian Creed over time has been used in public worship less and less frequently. However, part of it can be found as an "Authorized Affirmation of Faith" in the main volume of the Common Worship liturgy of the Church of England published in 2000.

Designed to distinguish Nicene Christianity from the heresy of Arianism, the Athanasian Creed traditionally was recited at the Sunday Office of Prime in the Western Church. It has not been commonly used in the Eastern Church.

Athanasius I of Alexandria (c. 296–298 – 2 May 373), also called Athanasius the Great, Athanasius the Confessor, or, among Coptic Christians, Athanasius the Apostolic, was a Coptic church father and the 20th pope of Alexandria (as Athanasius I). His intermittent episcopacy spanned 45 years (c. 8 June 328 – 2 May 373), of which over 17 encompassed five exiles, when he was replaced on the order of four different Roman emperors. Athanasius was a Christian theologian, a Church Father, the chief defender of Trinitarianism against Arianism, and a noted Egyptian Christian (Egyptian) leader of the fourth century.

Conflict with Arius and Arianism as well as successive Roman emperors shaped Athanasius' career. In 325, at the age of 27, Athanasius began his leading role against the Arians as a deacon and assistant to Bishop Alexander of Alexandria during the First Council of Nicaea. Roman emperor Constantine the Great had convened the council in May–August 325 to address the Arian position that the Son of God, Jesus of Nazareth, is of a distinct substance from the Father. Three years after that council, Athanasius succeeded his mentor as pope of Alexandria. In addition to the conflict with the Arians (including powerful and influential Arian churchmen led by Eusebius of Nicomedia), he struggled against the Emperors Constantine, Constantius II, Julian the Apostate and Valens. He was known as Athanasius Contra Mundum (Latin for Athanasius Against the World).

Nonetheless, within a few years of his death, Gregory of Nazianzus called him the "Pillar of the Church". His writings were well regarded by subsequent Church fathers in the West and the East, who noted their devotion to the Word-become-man, pastoral concern and interest in monasticism. Athanasius is considered one of the four great Eastern Doctors of the Church in the Catholic Church. In his Easter letter of 367, Athanasius was the first person to list the 27 books of the New Testament canon that are in use today. He is venerated as a Saint in the Eastern Orthodox Church, the Catholic Church, the Coptic Orthodox Church, the Anglican Communion, and Lutheranism.