The ministry of a deaconess is a usually non-ordained ministry for women in some Protestant, Oriental Orthodox, and Eastern Orthodox churches to provide pastoral care, especially for other women, and which may carry a limited liturgical role. The word comes from the Greek diakonos (διάκονος), for "deacon", which means a servant or helper and occurs frequently in the Christian New Testament of the Bible. Deaconesses trace their roots from the time of Jesus Christ through to the 13th century in the West. They existed from the early through the middle Byzantine periods in Constantinople and Jerusalem; the office may also have existed in Western European churches. There is evidence to support the idea that the diaconate including women in the Byzantine Church of the early and middle Byzantine periods was recognized as one of the major non-ordained orders of clergy.

Eastern Orthodoxy, otherwise known as Eastern Orthodox Christianity or Byzantine Christianity, is one of the three main branches of Chalcedonian Christianity, alongside Roman Catholicism and Protestantism. Like the Pentarchy of the first millennium, the mainstream Eastern Orthodox Church is organised into autocephalous churches independent from each other. In the 21st century, the number of mainstream autocephalous churches is seventeen; there also exist autocephalous churches unrecognized by those mainstream ones. Autocephalous churches choose their own primate. Autocephalous churches can have jurisdiction (authority) over other churches, some of which have the status of "autonomous" which means they have more autonomy than simple eparchies.