Movies with mental illness theme

I saw the movie Spider many times but I still don't get it.

Snow Cake - This is an amazing movie. I love it. One of the main characters has autism.

The Machinist

Great thread, I will be watching all of these!

I've watched recently: The Ward which is (in my opinion failed) attempt to portray dissociative identity disorder (multiple personality disorder) and I Am Sam about autism (not an mental illness but I think it's worth watching).

That Wikipedia list seems quite inclusive.

Drop Dead Fred.

Just watch this

Drop Dead Fred

The Snakepit.

Black Swan.

"Manic" features a character with bipolar.

Others:

-Ordinary People (depression, suicidal ideation, hospitalization. Won the 1980 Oscar for Best Picture)
-Shutter Island (I won't tell you the main condition, or I might ruin the film for you)
-Primal Fear with Edward Norton (Dissociative Identity Disorder, or what used to be known as Multiple Personality Disorder)
-Sybil (DID)
-Child of Rage (Reactive Attachment Disorder and homicidal ideation)
-someone else mentioned autism, and I wouldn't consider it a mental illness exactly (maybe it technically is? With mental illness, I tend to think of conditions that are progressive or perhaps emotionally generated, such as Schizophrenia (progressive) - but maybe it's technically considered a mental illness?). It's a developmental delay, but if you want to count autism, then I'd recommend both "Temple Grandin" and "Rain Man"
-Phoebe in Wonderland (little girl has Tourette's, but also OCD)
-Taxi Driver (OCD along with many more problems)
-The Three Faces of Eve (DID)
-Thirteen (self-injury/ depression)
-House of Cards (autistic like fugue state, almost. Hard to explain. The little girl retreats into her self after watching her father die)
-The Good Son (I would say the kid played by Macauly Culkin is a little psychopath...make your own call ;))
-Identity with John Cusack
-K-PAX
-The Aviator (about Howard Hughes, so severe OCD)

Sybil - Dissociative Identity Disorder (based on a true story too)
Donnie Darko - Schizophrenia (although it's not the theme of the movie, the main character is a schizophrenic INFP)