A recruit to the Night’s Watch, Grenn is youth of 16. A head taller than Jon Snow, thick-necked and muscular, he is both slow in thought and in action. This fact, plus his size, leadshim to be derisively nicknamed “Aurochs” by Ser Alliser Thorne, Castle Black’s master-at-arms. He has a friendly rivalry with Pypar.
The actor cast in the roll is somewhat older, and is certainly much shorter than the character as described.