Saint Mark's feast day is April 25th.
The Gospels are probably the most important written works of all of Christianity. It is from their words, that the Word of God has been carried in writing to millions of people throughout the centuries. Each of these writers is represented by a creature. As one of the four Gospel writers, and one of the seventy disciples of Jesus Christ, Saint Mark is considered by the Church to represent the Lion. This was taken from a vision seen by the Prophet Ezekiel around 625 years B.C.:
And every one had four faces: the first face was the face of the cherub, and the second face was a human face, and the third the face of a lion, and the fourth the face of an eagle. - Ezeckiel 10:14