Identity Crisis

I know that many of us may have had an identity crisis, especially when we are young, or when we become older.

Here I suggest some readings or films that deal with identity crisis in some way. Could you add more?

The Metamorphosis, by Franz Kafka (a novel)
Groundhog Day (atrapado en el tiempo), a film directed by Harold Ramis

Is being yourselves important to you? What does "being oneself" mean?