Pycelle

Pycelle is a character in Game of Thrones. He is played by Roy Dotrice and will appear in the first season.

Pycelle is the Grand Maester of the Seven Kingdoms. The Grand Maester is the King's personal maester, a learned man wise in history, science and medicine who also provides counsel. The Grand Maester sits on the King's small council, which orders the realm in the name of the King.

In the books
In the Song of Ice and Fire novels Pycelle is in his eighties and has been Grand Maester for forty years, beginning his service in the closing months of King Aegon V Targaryen's reign and maintaining the post for the entirety of the reigns of King Jaehaerys II, King Aerys II and now King Robert. He was a colleague of Tywin Lannister during his tenure as Hand of the King. He has a long white beard which he has been growing for decades and is very proud of.

The Grand Maester is the titular head of the order of the maesters, although his service in King's Landing, some distance from the Citadel in Oldtown, means that the Conclave of Archmaesters has some degree of autonomy from the Grand Maester.