symbols of the evangelists
The Evangelists are symbolized in art by emblematic figures, usually winged: a human head, a lion, an ox, and an eagle.
These are described in the vision of Ezechiel in his prophecy, and in that of Saint John in his Apocalypse.
The human head indicates Saint Matthew, because he begins his Gospel with the human ancestry of our Saviour.
The lion, the dweller in the desert, is emblematic of Saint Mark, who opens his narrative with the mission of Saint John the Baptist, "the voice of one crying in the wilderness."
The sacrificial ox is the symbol of Saint Luke, for his Gospel begins with the story of the priest Zachary.
The eagle, soaring far into the heavens, is the emblem of Saint John, who, in the opening words of his Gospel, carries us to Heaven itself: "In the beginning was the Word, and the Word was with God, and the Word was God."
New Catholic Dictionary