The movie Unbreakable by M. Night Shyamalan is about a man, David (Bruce Willis), who thinks that he is normal— average, nothing particularly special. His identity is revealed to him by Elijah (Samuel L. Jackson) who is crazy, searching for his own identity by discovering someone who is his opposite--which happens to be David. Each man ends up defining himself (finding his identity) in comparison to someone else.
We might even see this is Shymalan's Signs. Rev. Graham Hess (Mel Gibson) is forced through the danger of an alien invasion to search for his identity—having lost his faith when his wife was killed in a car accident, when (as a pastor) he lost his faith in God and direction in his life.
In both movies, identity is at the center, and the search by individuals to find a way to know and define themselves.