In Christian tradition, the Four Evangelists are Matthew, Mark, Luke, and John, the authors attributed with the creation of the four canonical Gospel accounts. In the New Testament, they bear the following titles: the Gospel of Matthew; the Gospel of Mark; the Gospel of Luke; and the Gospel of John.
The gospels of Matthew, Mark, and Luke are known as the Synoptic Gospels, because they include many of the same stories, often in the same sequence or even verbatim. While the periods to which the gospels are usually dated suggest otherwise, convention traditionally holds that the authors were two of the Twelve Apostles of Jesus, John and Matthew, as well as two "apostolic men", Mark and Luke, whom Orthodox Tradition records as members of the 70 Apostles (Luke 10):
They are called evangelists, a word meaning "people who proclaim good news", because their books aim to tell the "good news" ("gospel") of Jesus.
In iconography, the evangelists often appear in Evangelist portraits derived from classical tradition, and are also frequently represented by the symbols which originate from the four "living creatures" that draw the throne-chariot of God in the vision in Ezekiel 1 reflected in the Book of Revelation (4:6–9ff), referred to as the four 'Seraphim', though neither source links the creatures to the Evangelists (of course the depiction of the Seraphim predates in chronology the writing of the New Testament which portrays the writers John, Luke, Mark, Matthew as symbolically embodied by the four Seraphim). Images normally, but not invariably, appear with wings like angels. When the symbols of the Four Evangelists appear together, it is called a Tetramorph, common in the Romanesque art of Europe such as church frescoes or murals.
The meanings accruing to the symbols grew over centuries, with an early formulation by Jerome, and were fully expressed by Rabanus Maurus, who set out three layers of meaning for the beasts: representing first the Evangelists, second the nature of Christ, and third the virtues required of a Christian for salvation. These animals may have originally been seen as representing the highest forms of the various types of animals: man, as king of creation, as the image of the creator; the lion, as king of beasts of prey (meat-eating); the ox, as king of domesticated animals (grass-eating); the eagle, as king of birds.
Each of the symbols is depicted with wings, following the biblical sources first in Ezekiel 1–2, and in Revelation. The symbols are shown with, or in place of, the Evangelists in early medieval Gospel Books, and are the usual accompaniment to Christ in Majesty when portrayed during the same period, reflecting the vision in Revelation. They were presented as one of the most common motifs found on church portals and apses, as well as many other locations.
When surrounding Christ, the figure of the man usually appears at top left—above Christ's right hand, with the lion above Christ's left arm. Underneath the man is the ox and underneath the lion is the eagle. This both reflects the medieval idea of the order of "nobility" of nature of the beasts (man, lion, ox, eagle) and the text of Ezekiel 1:10. From the 13th century, their use began to decline, as a new conception of Christ in Majesty, showing the wounds of the Passion, came into use. In Evangelist portraits, they sometimes appear to dictate to the writing evangelist.
Matthew is often cited as the "first Gospel account", not only owing to its place in the canon, but also in view of the patristic witness to this effect. However, most biblical scholars see the gospel account of Mark as having been written first and John's gospel account as having been written last of the four.
It is customary to refer to the gospels phrased as "the Gospel of Matthew" or as "Matthew's Gospel", and so on.
General info from Wikipedia.org