Dissociative identity disorder

Mental illness with multiple personality states

Dissociative identity disorder (DID), previously known as multiple personality disorder (MPD), is a dissociative disorder characterized by the presence of at least two personality states or "alters". The diagnosis is controversial and remains disputed. Proponents of DID support the trauma model, viewing the disorder as an organic response to severe childhood trauma.

From Wikipedia, under CC BY-SA. More on occurri.