John Coffey is a fictional character from the novel "The Green Mile" by Stephen King. He is a large, gentle man who is wrongfully imprisoned for the murder of two young girls. Despite his intimidating appearance, Coffey possesses a kind heart and a miraculous ability to heal others. Coffey's character is central to the story, which explores themes of compassion, injustice, and the supernatural. He has a unique connection to the electric chair, known as "Old Sparky," where he faces his fate. His story raises questions about morality and the nature of true evil.