The Koukoulion is a traditional headress worn by monks of the highest degree in the Eastern Orthodox Church

Eastern Orthodox Church

The Orthodox Church, officially called the Orthodox Catholic Church and commonly referred to as the Eastern Orthodox Church, is the second largest Christian denomination in the world, with an estimated 300 million adherents mainly in the countries of Belarus, Bulgaria, Cyprus, Georgia, Greece,...

. (See Degrees of Eastern Orthodox monasticism

Degrees of Eastern Orthodox monasticism

The degrees of Eastern Orthodox monasticism are the stages an Eastern Orthodox monk or nun passes through in their religious vocation.In the Eastern Orthodox Church, the process of becoming a monk or nun is intentionally slow, as the monastic vows taken are considered to entail a lifelong...

.)

From the 17th century, following the reforms of Patriarch Nikon

Patriarch Nikon

Nikon , born Nikita Minin , was the seventh patriarch of the Russian Orthodox Church...

, the upper vesture worn by monks of the Great Schema (skhimonakh) is in the form of a pointed hood with two long Lappet

Lappet

A lappet is a decorative flap or fold in a ceremonial headdress or garment. They were a feature of women's headgear until the early 20th century. They remain strongly associated with religion. A bishop's mitre has two lappets sewn to the back of it. The most famous usage of lappets occurs on the...

s which cover the back and breast. It is black in color, and embroidred with crosses, six-winged seraphim, and the text of the Trisagion

Trisagion

The Trisagion , sometimes called by its opening line Agios O Theos or by the Latin Tersanctus, is a standard hymn of the Divine Liturgy in most of the Eastern Orthodox Churches, Oriental Orthodox Churches and Catholic Churches.In those Churches which use the Byzantine Rite, the Trisagion is chanted...

. It is worn above the mandyas (monastic mantle), and is the same for both monks and nun

Nun

A nun is a woman who has taken vows committing her to live a spiritual life. She may be an ascetic who voluntarily chooses to leave mainstream society and live her life in prayer and contemplation in a monastery or convent...

s. In the context of monastic vows it is called the koukoulion of kindliness, and the helmet of salvation. The koukoulion replaces the klobuk

Klobuk

thumbA klobuk is an item of clerical clothing worn by Eastern Orthodox and Eastern Catholic monastics and bishops, especially in the Russian tradition...

 which is worn by the monastics of lower ranks.

The Patriarch of Moscow and all Russia wears a white koukoulion with a "Zion", a stiffened point topped by a cross. He wears this ex officio, whether or not he has been tonsure

Tonsure

Tonsure is the traditional practice of Christian churches of cutting or shaving the hair from the scalp of clerics, monastics, and, in the Eastern Orthodox Church, all baptized members...

d into the Great Schema. Koukoulia are also worn by the primate

Primate

A primate is a mammal of the order Primates , which contains prosimians and simians. Primates arose from ancestors that lived in the trees of tropical forests; many primate characteristics represent adaptations to life in this challenging three-dimensional environment...

s of certain other Orthodox Churches, for example the Catholicos-Patriarch of All Georgia

Catholicos-Patriarch of All Georgia

Catholicos–Patriarch has been the title of the heads of the Georgian Orthodox Church since 1010. The first Catholicos–Patriarch of All Georgia was Melkisedek I...

.