A commoner who was one of the recruits that arrived at Castle Black at the same time as Jon Snow. He has a thick neck and is stronger and older than Jon. His friends mock him for being slow and his clumsiness.
Like Jon, he suffers verbal abuse at the hands of Aliser Thorne, who nicknames Grenn “Aurochs” for his size. He is reluctant to make friends with Jon, who is younger than him and can beat him at swordfighting, but Jon offers to help train him. When Samwell arrives at Castle Black, Grenn is reluctant to protect him from Thorne’s cruelty, but the two become friends. He is named to the rangers when the recruits complete their training.