This document provides an analysis of the psychological disorders exhibited by the character Teddy Daniels/Andrew Laeddis in the film Shutter Island. It discusses how he suffers from dissociative identity disorder, schizophrenia, and delusional disorder as evidenced by creating an alternate identity as Teddy Daniels and inventing an elaborate conspiracy theory about the hospital. Symbolism of water and fire in the film represent his mental state and the boundary between sanity and insanity. The document will also discuss lobotomy and changes between the DSM-IV and DSM-5 criteria for these disorders.