Aemon

Aemon is a recurring character in Game of Thrones. He is played by Peter Vaughan and debuts in the third episode of the first season.

Aemon is the maester at Castle Black and is one of Lord Commander Jeor Mormont's closest advisers. He was once a member of House Targaryen before he joined the order of maesters and dropped his house name, but this has been long forgotten by most.

Season 1
After Tyrion Lannister has arrived at Castle Black, Maester Aemon asks him to to urge the King to send more men to the Night's Watch: there is severe lack of men to defend the Wall. They discuss the coming winter, and Aemon assures Tyrion that the next winter will be long and terrible.

When Jon Snow and the other new recruits are done with their first training, Maester Aemon gives the men their new assignments. Jon is to become Jeor Mormont's steward, which is a great disappointment to Jon: he had hoped to become a ranger. Samwell Tarly reminds Jon that being a steward for the Lord Commander might mean that Jon is being groomed for a high position amongst the Night's Watch.

When Jon hears about Eddard Stark's imprisonment, he is torn between his loyalty to the Night's Watch and his love for his family. Master Aemon is aware of Jon's struggle and reveals to him that his real name is Aemon Targaryen, and that he is a long forgotten uncle of the Mad King. He sat and waited on the Wall whilst he heard about his family being butchered during Robert's Rebellion and the few survivors fleeing into exile, and did nothing: after having joined the Watch, his duty was with his brothers there and no longer with his house. Aemon explains that this was a difficult decision; yet he had to make it and that one must live with the consequences of one's choices for the rest of one's life.

In the books
In the Song of Ice and Fire novels, Maester Aemon is a hundred years old and widely believed to be one of the oldest living men in all of Westeros. He has been on the Wall for almost seventy years and is known for his great wisdom, wise counsel and trusted judgement. He is the third son of King Maekar I Targaryen, the brother of King Aegon V Targaryen ('Egg' from the Dunk and Egg short stories by George R.R. Martin), the uncle of King Jaehaerys II Targaryen and thus the great-uncle of the Mad King and the great-grand-uncle of Daenerys Targaryen.

For the TV series Jaehaerys II has been removed from the roll of kings, making Aemon more closely related to Daenerys and Viserys.