Boccaccio might have an issue with that.
Alongside Twain, I’d nominate Edgar Allan Poe for the American spot. Poe is the father of detective fiction, which I think deserves some sort of nod here. Without Poe, there may not have been a Sherlock Holmes, a Hercule Poirot, or in later days a Nero Wolfe or Sam Spade.
And of course, Poe was a hundred times the poet that Twain was.
The problem with Dickens is that up until maybe the mid 40s, he was not considered serious literature any more than Thomas Kinkade’s contemporaries consider him serious art (“God bless us, Everyone!” ring any bells?). A more apt comparison may be Neil Gaiman, who also made his bones with serialized stories in disreputable formats; His merits are obvious, but I don’t think he’s what literary Britons aspire to be.
It IS sort of obvious, but the tricky part is that “Italy” wasn’t a counbtry in Dante’s day, so he wasn’t “Italian,” strictly speaking.
Of course, in that same sense, Goethe wasn’t German," but I included him as a German.
I think we can agree that, in most of the Western world, Dante is the most revered writer or poet working in the Italian language.
I beg to differ. Independent People can stand shoulder to shoulder with most of Shakespeare’s work.
Norway has Hamsun, and Undset.
The U.S. has John Ford, our Shakespeare.
For Canada, the first question is in which language? I would dispute Alice Munro, neither having read any nor having been forced to read any in high school. (The true measure of a piece of Canadian literature is that it is something they make you read in high school because no sane person would read more than 20 pages of it in the real world. 
) I’ll throw out some other possibilities -
Roberston Davies
Michael Ondaatje
Margaret Atwood
Stephen Leacock
Carol Shields.
On the French side of things, I immediately think of Michel Tremblay.
One of the hardest things about Canadian literature is that we are so obsessed with exploring and finding our own identity as separate from the US and the UK. There is a lot of excellent literature written in Canada that is completely unknown outside the country.
I think I’d have to go for Gogol too. Tolstoy can’t match Gogol for style or linguistic depth, which is Shakespeare’s greatest strength. Although Tolstoy probably approaches closer to Shakespeare on, what do you call, emotional scope?
Well, ditto for Shakespeare. And Hitchcock.
Isn’t it pretty much a cliche that the great artists are rarely appreciated in their lifetimes? (I can’t wait to die.)
I like the Poe suggestion. As regionalized as the US is, I wonder if a quadfecta of sorts would be more suitable (though totally cheating).
East: Edgar Allan Poe
South: William Faulkner
Midwest: Mark Twain
West: John Steinbeck
I love Hemmingway, but he doesn’t really seem to carry a nationality with his writing.
I don’t think that comparison really flies - did Ford write his own screenplays? I understand the idea of director as auteur, but it seems to me we’re dealing strictly with the written medium here.
ETA: Although Poe’s good (though I never thought he was much of a poet), he seems a little too one-note to be compared to Shakespeare.
I like Twain for the USA, or maybe Ambrose Bierce, purely from the “playful language” perspective. The thing about Shakespeare that makes me sit up and take notice is his iconoclastic approach to language…punnery, sarcasm, coined phrases, double entendres etc. Twain and Bierce both did this extensively. They weren’t quite as subtle as Shakespeare, but those elements were there.
For what it’s worth, I like Nooteboom but I think Mulisch is read in the US slightly more frequently. However, the Dutch fiction author probably read the most in the US is Janwillem van de Wetering (I’m guessing, I don’t have any research to back me up). That might make for a good sister thread, instead of Shakespeare, who is the Agatha Christie of your country?
I haven’t read Reve, what would you recommend?
Ben Jonson got it right:
I think this is the problem with the assumption in the OP. Shakespeare was such a towering, influential writer that I really don’t think any other country has produced an equivalent, writing in English.
I was going to post something similar to AK84 - Shakespeare is (English) Canada’s Shakespeare, in the same sense - he is part of our shared heritage of the English language.
And then, for Canada, I think Le Ministre de l’au-delà raises a key point, about the bilingual nature of the country. I would take that point further, and say that I do not think it is possible for Canada to produce a Shakespeare in the sense the OP is getting at - one that resonates with all Canadians. The reason is that the language of his plays is so important for his reputation - and since not all Canadians share the same mother tongue, it is highly unlikely that any author, writing in English or in French, could have the same national impact that Shakespeare could have for Britain.
For Israel, you have Bialik and Alterman for poets and Agnon (and maybe Kishon) for writers…
… but actually, the Israeli Shakespeare is whoever wrote the Old Testament.
The very first question I asked on the Dope (long-since vanished) was “Who was the second-greatest American humorist?” I started with the naive assumption that Mark Twain would be universally acknowledged as the greatest American humorist.
Boy, was I wrong. If there isn’t even consensus that Twain was the greatest American humorist, there sure as hell won’t be consensus about what American writer is universally recognized as our version of Shakespeare.
Other countries, I have no idea. I’ll just stand over here and watch y’all fight it out.
For Australia, the answer may be Henry Lawson, who wrote both poetry and prose, but is better regarded for his prose these days. The main competitor would be Patrick White.
Pushkin is quasi-officially “Russia’s Shakespeare”.
Melville is only in the running if you take Transcendentalism and the Symbolist works that came out of it seriously. Transcendentalism was one of the important religious/philosophical revolutions in this country but it’s rather heavy-handed and the same ideas have been done better since.
Jack London is immediately comparable to Hemingway and he doesn’t come out the winner. Hemingway’s use of language alone puts him above London.
You are way too impressed by Boomer visionaries. Vonnegut is a somewhat more philosophical Bierce without the ear for story construction.
Would Shaw and Wilde count more as Irish (for the country of their birth) or English (for the country where they spent most of their life and where most of their works were set)?
In any case another “Twain” as hands down winner of America. One reason has nothing to do with his writing even- his image is so iconic (the white suit [that he rarely wore giving lectures] and the cigar and the wild mane and moustache), but aside from that:
*The combination of tongue-in-cheek and absolute seriousness that sailed on the same raft in his books
*The output so prolific that his works can be divided into timeless and not-so-timeless (e.g. as Shakespeare had Hamlet and King Lear Twain had The Adventures of Tom Sawyer and The Adventures of Huckleberry Finn; like Shakespeare had *Corolianus *and *Henry VIII *he had *The Gilded Age *and The American Claimant, as Shakespeare had his sonnets Twain has his short stories and his essays)
*The use of history (and enormous liberties taken with same- often for fun) in his works such as The Prince and the Pauper and A Connecticut Yankee in King Arthur’s Court
*An agnosticism if not nihilism that is sometimes very subtle and sometimes overt in his characters and his letters
*Many of his greatest works are firmly and squarely standing in American soil and could not be otherwise (very difficult to imagine Huckleberry and Jim going down the Danube or the Amazon) just as Shakespeare’s history works are so thoroughly English (though as Shakespeare moved to Verona and Venice in some great plays Twain could “travel” as well)
*The combination of crowd pleasing and greatness in his works
*The incredible layers of his work. I loved Tom Sawyer when I was a boy. I read it again in my 20s and loved it again and picked up on many things that went over my head as a child.
Of course I love Twain’s non-fiction writing more than most of his fiction. One of the few things that can move me to tears is the writing he did when his daughter Susie died and the writing he did on Christmas Eve 1909- the day his daughter Jean died; if you have it in you to be moved to tears by century old words those will do it.
And his quotability. Twain was on the surface- and I suspect to much of the bedrock- a sardonic and cynical fellow, and yet has some of the most emotionally moving prose. The funny bickering and mutual suspicion and curiosity and far from “love connection” Adam and Eve go through, and then the very short ending, after their explusion and move towards understanding and reliance on one another,
throws you for a loop. (All the more moving when you realize he wrote it when his own wife had just died.)
Anyway, my two bits to an already much given response.
Others I’d posit if not as Shakespeares but perhaps Marlowes or Johnsons would be Benjamin Franklin, Faulkner, Walt Whitman, and perhaps even Dorothy Parker and Ogden Nash.
Quentin Tarantino.
At least that’s what I told my English teacher in HS knowing it would piss her off.