"K-PAX" is a science fiction novel written by Gene Brewer, first published in 1995. The story follows Prot, an enigmatic patient at a mental institution who claims to be an alien from the planet K-PAX. As he interacts with the staff and other patients, his extraordinary knowledge and calm demeanor challenge their perceptions of reality and mental illness. The novel explores themes of identity, sanity, and the nature of existence. Through Prot's experiences and insights, the narrative raises questions about the human condition and the possibility of life beyond Earth. The book has gained popularity and was adapted into a film in 2001, starring Kevin Spacey and Jeff Bridges.