Prophet
A Prophet is a person who speaks of events to come, on instruction from Heaven. Castiel refers to them as "mouthpieces and conduits for the inspired word."
Prophets are given the power to see either future or current events by God. These prophets are instrumental to the plans of God and are therefore top priority to the angels. Thus, each Prophet of the Lord is connected or tied to an Archangel. Should anything try to harm them, an archangel will come to their aid. Should a demonic presence so much as approach a prophet, an archangel will step in, and the "Wrath of Heaven" shall fall upon the Demon.
In 5.17 99 Problems, Castiel claims that Leah is not a prophet because he has every prophet's name seared into his brain, and assumingly so does all Angels.
Prophets in Supernatural
Chuck Shurley
Chuck Shurley is a prophet of the Lord, and is the author of the Supernatural books. He makes his first appearance in 4.18 The Monster At The End Of This Book. He made his last appearance in 5.22 Swan Song. He was given the ability to see future events concerning the Winchester brothers. His current location is unknown; he vanished into thin air at the end of 5.22 Swan Song.
Luke
Castiel makes a reference to Luke in 4.18 The Monster At The End Of This Book. Although he was not seen in the episode. He wrote a number of books of the New testament known as the Gospel of St Luke.
Trivia
Castiel also makes references to Luke, is reputed to be the author a number of books of the New testament known as the Gospel of St Luke.
Castiel later informs Dean that one day these book will become known as the Winchester Gospels.
Prophets in Judaism Lore
In Judaism, a prophet is seen as a person who is selected by, and speaks as a formal representative of God, and the intention of the message is always to effect a social change to conform to God's desired standards initially specified in the Torah dictated to Moses[citation needed].
The prophetic assignment is not always portrayed as positive in the Hebrew Bible, and prophets were often the target of persecution and opposition. God’s personal prediction to Jeremiah, “Attack you they will, overcome you they can’t,” was fulfilled many times in the Biblical narrative as Jeremiah warned of destruction of those who continued to refuse repentance and accept more moderate consequences. This information was retrieved from http://en.wikipedia.org/wiki/Prophet
