Identity crisis

Note: This tag may need better name to make it applicable to more positive cases of reveals about one's identity. As when there's no crisis, but rather gleeful acceptance of it or simple acknowledgement of it. Generally cases where the protagonist is told "you're not who you think you are".

Unlike amnesia, the protagonist has no memory loss, or does not perceive themselves as having such.

This also includes cases when the identity crisis is a major plot point/theme not related to the protagonist (e.g. their companion or other major character in the plot).