"Harry and Tonto" - the director (Paul Mazursky) co-wrote this. Every human theme is explored, but in a very interesting way. There's some great humor, and its just perfect - my favorite movie.
https://www.patreon.com/LoyalOpposition

Not sure "the greatest" can be applied to any original screenplay, but my highly rated favourites would include :

1. Magnolia - Paul Thomas Anderson
2. A Very Long Engagement - Jean-Pierre Jeunet
3. Fargo - The Coen Brothers
4. Incendies - Denis Villeneuve
5. The Past - Asghar Farhadi
6. In A Better World - Anders Thomas Jensen
7. The Sea Inside - Alejandro Amenábar
8. Apocalypse Now - John Milius & Francis Ford Copolla
9. A Woman Under the Influence - John Cassavetes
10. Short Cuts - Robert Altman

"The Perfume"

Infinite Space
Written by me, Jordan Barber. Check it out online.
All your screenplays suck except for mine.
https://ca.linkedin.com/pub/jordan-barber/78/125/737

American Beauty
Titanic (great script!)
The Crying Game
An American Tragedy (unproduced)
The Crowded Room (unproduced, James Cameron)
Casablanca
The Deer Hunter
Aaron & Sara (unproduced)

Hmm, "the greatest original screenplay" implies one but you've listed 5, so I guess I'll do the same haha
Song of the Sea, Moonrise Kingdom, The Royal Tenenbaums, Up, and Little Miss Sunshine.
However, early word for Inside Out seems pretty amazing, and after what the director did on Up, I wouldn't be surprised to see Inside Out's screenplay - which is sure to be complicated and deep with all the emotions and switching back and forth between inside and outside the mind - turn out to be amazing and make some big waves.
Check out my blog!
http://animationalley.blogspot.com

Sunset Blvd.
Les Diaboliques
Psycho
"Some men are coming to kill us. We're gonna kill them first." [fight7]

The Sting (1973)
Volker Flenske: (While torturing David) I don't know why you're doing this to yourself!

by EastAsianMafia » 9 minutes ago (Mon Jan 25 2016 10:23:39)
IMDb member since February 2015
Dividiiiiium's real name is Jordan Barber. 34 yo. UK.
He is racist and a homophobe.
http://www.imdb.com/board/22258603/?ref_=fn_al_nm_1
https://ca.linkedin.com/pub/jordan-barber/78/125/737
he above poster's name is Timothy Williams from Brisbane Australia. He is probably best known as Chemical_Dali but he uses several different sock puppets on multiple websites, not just stalking and harassing me, but several other individuals too.
He has mental health problems of which he refuses to find help for.
You can find his imdb page here:
http://www.imdb.com/board/25577398/?ref_=tt_ov_dr
He's the true definition of a coward who likes to harass people online and post their photos on the internet.
If you want to see how fat he is, take a look at his flab here:
http://www.anony.ws/i/2015/09/26/TimothyWilliams.jpg
He's a very desperate individual who logs onto imdb with countless sock puppets pretending to people that he's a big shot screenwriter who gets paid upto $150,000 per rewrite job
but in reality he's a sound recordist who can barely get by working on student films.
He can also be seen in the following video 'Woollo (2011)" at the top of this vimeo page:
https://vimeo.com/channels/554465/44783671
between the 14:20 to 14:40 mark dressed as a construction worker who says the line "Well, someone's stole our wood."

Dividiiiiium's real name is Jordan Barber. 34 yo. UK.
He is racist and a homophobe.
http://www.imdb.com/board/22258603/?ref_=fn_al_nm_1
https://ca.linkedin.com/pub/jordan-barber/78/125/737

Eraserhead 2000
Roger Keith "Syd" Barrett - 1946 - 2006

Probably Taxi Driver. I don't know how it wasn't nominated for original screenplay though.

Snowcake, obviously.
Its all your fault that I love that movie now. Do you know that?
And so, the lion fell in love with the lambwhat a stupid lamb

Why thank you Kayla; what did you end up renting the other day?

Its on my top 5 for sure.
And yes, I bet Braeden does have an opinion about the scent of Juno's feet. For, there has never been a time in my life where he was without an opinion.
They are however, usually right.
And so, the lion fell in love with the lambwhat a stupid lamb

the coen brothers have quite a few on the list but the foot fetish movie beats them all

I agree, for sure.
I mean really that foot fetish film rocked.
And so, the lion fell in love with the lambwhat a stupid lamb

Well thats the whole thing with these boards, or anything else you might read or hear: take everything with a grain of salt. One should try and take into account many factors when debating or comparing information with another's. However, it would be wrong for you, or anyone else for that matter, to talk down to someone for their personal preference or opinion.
For the record, just because someone has seen more films than someone else, doesn't mean that person will be able to judge a movie better, have a better taste in film, or know anything more than the other person might. For example, Mr. Foot Fetish could have, in my opinion, a far superior taste in film to you, even though he has seen fewer movies.

Braeden, Blackbelt
You are correct, the original post did not have a minimum number of films for a person to have seen, in order to base their opinion on..so lets say someone saw 5 crappy filmsand that person had a foot fetishone of the bad films was "Attack of the 500 Smelly Feet"..so that person would post "Attack of the 500. is the best movie in the universe !
Z-Man

I dont think the OP had a minimum number of films you had to have seen to reply

Your list is based on insufficient input and personal opinion..
How is this possible you say ??
Well, lets say your opinion is based on 500 films, that you have seen.
But.Joe Blow or Mary Smith have seen 10,000 films, or 20 times more films then you have seen, their opinion would be based on more input.
I have seen over 100,000 films so my input is based on better databut it would still be just " My Personal Opinion."
Z. Ray Wakeman