During the Battle of Castle Black, Cooper takes part in defending the Wall against Mance Rayder's forces. When Castle Black's inner gate is threatened by the giantMag Mar Tun Doh Weg, he accompanies Grenn, Donnel Hill, and other three black brothers to defend it. Although he initially wavers and considers fleeing upon seeing the giant, he is convinced by Grenn to stay and fulfill his oath to the Night's Watch. They successfully kill the giant, but all of the black brothers are slain in the process. Their bodies are discovered by Jon Snow and Samwell Tarly after the battle.
After the arrival of Stannis Baratheon and his forces, though not seen Cooper is among the numerous bodies of fallen black brothers burned in Castle Black's courtyard.
In the A Song of Ice and Fire novels, there is no character by this name. Of the four men that accompany Donal Noye to face Mag the Mighty, only one is mentioned by his name - Spotted Pate of Maidenpool. The names of the other three are not mentioned.