Favorite screen or stage portrayal of a character's descent into madness (spiral!

Favorite screen or stage portrayal of a character's descent into madness (spiralling or otherwise)?

Hard for me to choose, but I just saw Les Blessures Assassines, and I have to say, Sylvie Testud truly rocked it out. Your picks?

"Falling Down" is a pretty good movie about a guy's slide into paranoid personality disorder.

"Girl, Interrupted" is a great book, and pretty good movie, about several young girls' battles with delusions, personality disorders, and schizophrenia.

"The Basketball Diaries" is a great movie that tells the story of a star athlete who's mental decline is linked to heroin addiction. "Leaving Las Vegas" is also a really good movie graphically depicting the mental toll of alcohol addiction, and co-dependence. And, of course, you can see Tony Montana's descent into cocaine madness in the movie "Scarface."

My personal favorite book is "The Bell Jar," by Sylvia Path. (There's an old movie made from it, but I haven't seen it.) A semi-autobiographical story about a young woman's struggle with crippling depression, at a time when the cure was worse than the disease. Truly heart-breaking.

And, finally, my favorite movie along these lines is "Dead Poets Society." A successful young man with his whole life ahead of him commits suicide.