K-PAX is a 2001 American-German science fiction-mystery film based on Gene Brewer's 1995 novel of the same name, directed by Iain Softley, starring Kevin Spacey, Jeff Bridges, Mary McCormack, and Alfre Woodard. Synopsis: A psychiatric patient claims to be an alien from the planet K-PAX. During his treatment, the patient demonstrates an outlook on life that ultimately proves inspirational for his fellow patients and especially for his psychiatrist.

References:
https://en.wikipedia.org/wiki/K-PAX_(film)