Old Man's War is a military science fiction novel written by John Scalzi. It is set in a future where elderly people can join the Colonial Defense Forces, a military organization that protects human colonies in space. The story follows John Perry, a 75-year-old man who enlists in the CDF and undergoes a rejuvenation process to become a young soldier. Old Man's War explores themes of mortality, identity, and the human cost of war. The book is known for its fast-paced action and engaging characters.
