From A Wiki of Ice and Fire
Osric Stark as depicted in Game of Thrones: Histories & Lore.
|Lord Commander of the Night's Watch
|In unknown (aged 70)
|A Feast for Crows (mentioned)
Osric was only ten years old when he was elected Lord Commander of the Night's Watch, making him the youngest chosen for that position. Maester Balder wrote The Edge of the World during Osric's rule of sixty years.