Final answer:
In the novel Ender's Game by Orson Scott Card, Graff allows the boy to hit Ender on the head as part of his training. The boy who hits Ender is named Stilson and he ends up getting severely injured and dying from the fight.
Step-by-step explanation:
In the novel Ender's Game by Orson Scott Card, Graff doesn't stop the boy from hitting Ender on the head because it is part of the training program designed to push Ender to his limits. Graff believes that Ender needs to face challenges and obstacles in order to develop his skills as a military leader. By allowing the boy to hit Ender, Graff is testing Ender's resilience and ability to overcome adversity.
The boy who hits Ender on the head is named Stilson. After the incident, Ender fights back and severely injures Stilson. Unfortunately, Stilson ends up dying from the injuries he sustained in the fight.