What Is The Best Psychological Thriller Ever?

Although it may seem dated to some, I still really like the original "Psycho" with Janet Leigh and Anthony Perkins.  Made in 1960 and directed by Alfred Hitchcock.

I may have already answered this so pardon me if it's double - I am kind of new to this - but for me Saw and Saw II were by far the best.  Hostel came in a close second, although that was a little hard to take at times.

The original Saw was an excellent flick, I might also suggest the original Cube.  American Psycho is another good movie, but the book is much, much better as often is the case... If you can stand subtitles, I would also suggest Pan's Labarynth.
Not in the horror catagory, but a good mind twister with a little action is another Christian Bale movie Equalibrium.

"Witness for the Prosecution" starrinig Tyrone Power, Marlene Dietrich, and Charles Laughton, directed by Billy Wilder, and based on an Agatha Christie play is superb.   It's a real psychological thriller, and you'll never see the end coming.

Rear Window, Alfred Hitchcock (old one) with James Stewart starring.  Have seen it several times and still leave the room in parts. :)

Oooooh - PSYCHOLOGICAL thrillers!

SHADOW OF A DOUBT is a GREAT Alfred Hitchcock movie starring Teresa Wright and Joseph Cotton.  She's a young girl in a small town, and he's her favorite uncle, who comes to visit.  Turns out Uncle Charlie may not be so nice after all...

THE SILENT PARTNER is a way-cool crime/thriller from Canada in the late 1970s.  Elliott Gould is a bank teller who thinks he's going to be robbed (by a SCARY CHristopher Plummer).  SO when the robbery happens, he diverts some of the money into his own bag, so it seems that the robber got away with a lot more money than he actually did.  Everything's fine, until the robber comes back wanting the money.  REALLY neat cat-and-mouse game.  (There's one extremely violent scene, though.)

SILENCE OF THE LAMBS has one of the most memorable movie villains of all times in Hannibal Lecter (Anthony Hopkins).  The interplay between him and FBI agent Clarice Starling (a wonderful Jodie Foster) makes this movie a classic.

GASLIGHT has a great performance by Ingrid Bergman as a woman who might or might not be going crazy.  And what's her husband (Charles Boyer) doing at night, anyway?

I echo the folks who have suggested REAR WINDOW and PSYCHO, and I'd add VERTIGO, with Jimmy Stewart as an investigator with a fear of heights.

Enjoy!

These are the ones that come to mind.

Jessa, you may have seen it but, if not, get "slingblade", Billy Bob Thornton was superb in it!-He wrote, directed and starred in the movie.

The shining with jack nickelson was a classic .

I just watched "Storm of the Century", based on a Stephen King book.  Don't know names of any actors, but it was definitely a thriller!

I think i am gonna have to go with Slingblade .Billybob Thorton is the best .

Bring out the popcorn and licorice.  When I rented the movie the first time, it was on VHS and was a two-pack.  My daughter and I watched it at night when it was snowing like in the movie (I lived in the mountains at the time).  The first tape was so scary, we had to wait awhile to watch the 2nd part of the movie!  But, we finally got the courage to watch it.  It was one of those movies you have to put your hands in front of your eyes in some parts.  Lol  Have fun!

Memento, directed by Nolan, is a marvelous piece... Also watch The Game, directed by David Fincher, and Vertigo by Hitchcock

The best thriller ever is hard candy!

Mr brooks is awesome

"The Machinist" with Christian Bale(weighing 115lbs)!

Lucky Number Slevin.... Has Josh Harnett and Bruce Willis... Very good, and you really never see the end coming.

Wicker Park, not  a thriller, but defiantly plays with your mind for awhile.

THE ORPHANAGE/EL ORFANATO! Do yourself a favor by watching this especially if youre a Guillermo del Toro fan aka Pans Labyrinth and The Devils Backbone

I'm sorry to disappoint, but the film I recall is title-less. I remember it good and it scared the bejusus out of me. But then, I was young. It's old, black and white, and I think it was English. There was an actor in it, but for the life of me I don't recall his name! I can see his face in my mind, it's frustrating! As I remember the story goes, a young crippled girl returns home from bording school or something like that, to the french Riviera where her father has a villa. She's lost contact with him and returns to find out what's happened. There's the young stepmother and her father's personal chauffeur, but no daddy! I can remember the body of the father turning up in her fire flickering bedroom at night, dripping wet and staring vacantly. Of course
she's made to believe it was a dream. There is one particular scene more than others concerning a dense lily pond in the huge veranda, where the driver, who decides to help the daughter, dives in to find what the young girl suspects is harbouring daddy's body. As he swims through the reeds and moss he sees beyond the murk, yes, you've guessed it, the said body. It looked so eerie! It gave me nightmares for weeks. But then I was an impressionable boy. If anyone out there knows what it's called or at least has an idea how to find out I'd be grateful if they could swing it my way. I wouldn't mind seeing it again myself, even if it doesn't have the same impact. I enjoy all the old classics. As a matter of interest, it has a twist to the finale, but I'll keep that under my hat, just in case anyone finds out what the title is and decides to give it a whirl!

I have one which has great atmosphere. The Spiral staircase, the original from the 40's is far superior to what is out there now. Give it a  whirl. The house on haunted hill is another. The Vincent Price version. Vertigo is brill for tension and suspense.

The shining of course!

I'm going to through out there a few because it sounds like you are seeking suggestions, or I just can't choose one.
Identity, John Cusack
The Butterfly Effect, Ashton Kutcher
Memento, Guy Pearce & Carrie-Anne Moss the bald traitor from the Matrix was also in this.
Danika, with Marissa Tomei.  Has been shot down alot for supposedly being plot-less and confusing.  To me, a good psychological thriller should be somewhat confusing, mind bending and require considerable thought.  But if you get it, then you'll know there is a clear plot and point to the movie.  While this isn't the best ever, worth a mention.