The Orthodox Church is the original church. During the time of the apostles there was only one church inexistence. If you were part Christian you were part of "the church." There was no denominations in existence at this time. The churches all believed in the same doctrine. We believed what as known as the Nicene Creed. This stayed the same till 1054. At this time the church was organized into various "Sees." Jerusalem, Constantinople, Rome, Alexandria, Antioch. Rome was the first among equals. In 1054 Rome's Pope, Pope Leo IX issued and edict in which he stated Papal Infallibility and Universal Jurisdiction. This is when the rest of the Orthodox Church rejected his edict and in response the Catholic Church excommunicated the rest of the Orthodox Churches and the Orthodox Churches excommunicated the Catholic Church. From this point on The original church was known was the Orthodox church and has kept all its doctrine the same. It has not changed since. Many heresies came through, but anyone who did not renounce there heresies, For example, Arius, was excommunicated from the church because he stated the Christ was not as high as the Father. Heresy's and change in the church were not tolerated. It has not changed since the apostles. We have kept the same doctrine, dogma, and Holy Traditions since. So in response to the question, you can say that the Orthodox church came from the apostles themselves as most of the sees where created by the preaching of the apostles. For example, the See of Alexandria was started by St. Mark, the apostle. If you search any church timeline online, you will see that the original church was the same.
There is an Orthodox Church and a Catholic Church. There is no Catholic Orthodox Church.
Eastern Orthodox Church (or the Christian Orthodox Church).
No, the Greek Orthodox church is a part of the Eastern Orthodox Churches.
Anglican Orthodox Church was created in 2001.
The Orthodox Church of Greece (Eastern Orthodox Church).
Its a faith (church). Bulgarians follow Orthodox church
The Coptic Orthodox Church
Yes, there are groups that split from the Eastern Orthodox Church. The so called "Nestorians," now known as the Church of the East, or the Assyrian Church of the East; the so-called "Monophysites," now known as the Armenian Apostolic Church, the Syrian Orthodox Church, The Malankara Church, the Ethiopian Tewahedo Church, the Coptic Church, and the Eritrean Orthodox Church; the Roman Catholic Church. All of these "splits" resulted in new organizations that have never reconciled completely with the Orthodox Churches. Also, splits more "within" the Orthodox Church that have been reconciled in some cases, and not in other cases (some small groups believe they they alone carry on the Orthodox Church, and that the current Orthodox Churches are no longer Orthodox) Old Rite or Old Believers, Old Calendarists (several different organizations), Catacomb Church in Russia (which is virtually extinct; new varieties seem to come into existence frequently). Nationalist driven splits-the Ukrainian Orthodox Church is the only large grop that insists on being on its own, while its Mother Church, the Russian Orthodox Church, does not sanction the unilateral declaration of "independence," as that is not how is has been traditionally done within the Church.
The Romanian Orthodox Church mainly follows the liturgical practice of the Greek Orthodox Church, rather than the Russian Orthodox Church, such as the use of the new calendar.
Abkhazian Orthodox Church was created in 2009.
Orthodox Church in America was created in 1924.
The population of Orthodox Church in America is 1,000,000.