Kevin Spacey is from the planet K-Pax, Jeff Bridges is the psychiatrist trying to help him. This is basically The Fisher King – Scifi edition (Bridges was in that too). This was a really good movie and again, the point here is not whether he is from space or not – you can conclude he is or isn’t based on what the movie provides, but that he touched the lives of others.
This movie was great – performance wise and theme wise. I would have liked a bit more exploration in what Spacey believes, but we got a lot, so I highly recommend this movie!