The Monstrous Inmate was a criminal imprisoned in the Kyln.
The inmate threatened Peter Quill upon his arrival at the Kyln. Before he could put his threat into action, Groot stuck his fingers up the inmate's nose and lifted him into the air. While the inmate screamed in pain, Rocket Raccoon made an example of him by warning the other inmates that anyone who wanted to harm Quill would have to go through them. Groot then dropped the inmate and left him whimpering on the floor.