I’m not sure who today’s Dr. Seuss would be, although I’d give the title to Mo Willems if I could. His Knuffle Bunny trilogy, while not quite up to Where the Wild Things are in terms of all-time great prose poems, is a wonderful piece, and I betcha most adults will be sniffling by the end.
George R. R. Martin is both pretty well known and highly regarded.
I guess one measure of ‘best-known’ would be readership outside genre. Both King and Rowling would have many readers who don’t routinely read within horror / kid fantasy but who would make the effort, just based on the name.
Another measure for ‘well-regarded’ would also be being seen to do something positive with their wealth and profile. Rowling has been very active in promoting literacy and a range of other causes that suggest she’s leveraging her fame for good rather than evil. Le Carre to a lesser extent.
Is there a possible contender in self-help books? Does anyone know if these sell in comparable quantities, and then would you regard the author of the Inedible Glop Diet as ‘well-regarded’ simply on sales? Oprah writes books, or does she just hold them up?
Best-regarded? That would be authors like JM Coetzee, Philip Roth, Haruki Murakami, Nadine Gordimer, Joyce Carol Oates, Toni Morrison, Martin Amis - the international Lit writers typically held up as “Nobel contenders” even if the Nobel has gotten a bit obscure over the years…
The nominations have all been for novelists. There are some non-fiction writers who are very famous and well-regarded. (But it may be best to ignore them here to avoid political hijacking :o )
I was a great fan once upon a time. Two of my favorite le Carré novels were his very first two, which were pure whodunnits. I also liked Secret Pilgrim, with each chapter a separate vignette. But I’ve been disappointed with his more recent books…
… and this is why. There is plenty of good non-fiction to read if I want to get angry about modern geopolitical trends. I read “espionage” books to be entertained, not to be lectured.
Terry Pratchett is known in the US mostly among nerds, but I understand that he has quite a broad fanbase in the British Isles. Still, “Brits and nerds” is a rather small slice of humanity.
Speaking of which, and since we’re asking about the world, are there any non-English-speaking authors we should be considering? A Chinese author, maybe?
I’d say the average Thai, or at least the average urbanized Thai, would at least recognize the names JK Rowling and Stephen King, from movies if not books, so that’s a good sign it would be either of them as far as being known worldwide goes. They would certainly know those over the names of any other authors mentioned in this thread.
The NYTimes has an editorial today arguing for Bob Dylan to win the Nobel. They cite Murakami as the the current odds favorite, with Roth and Oates mentioned; Coetzee won a few years ago. So, from a most-well-regarded standpoint, there’s a place to start.
Coetzee is a South African and a brilliant, brilliant writer - his book Disgrace is pretty much the best-crafted and written book I’ve read in the past couple of decades.
King and Rowling make sense in the discussion of most well-known, but don’t come close to most well regarded…
I was absolutely sure that I read about her death a few days ago but apparently not. Hope it’s not an omen.
Right? Michael Chabon is secretly my boyfriend. So secret that he’s never even met me, but he loves me deep down in his heart. I can feel it. But have you read “What Is The What?”? (Not sure how to punctuation that sentence. Anyway…) Mixed feelings.
Jonathan Franzen can blow me.
But on to the best-known living author. I’d say Stephen King and Rowling would be it. I’m trying to think of authors who you could mention to anybody – not just your nerd friends; I mean a random crowd anywhere – and they’d know who you’re talking about. And people known by name, not just what they’ve written, so “You know, the lady who wrote 50 Shades of Bullshit” (whose name I don’t know, btw) doesn’t count. The only authors I can think of who are still alive who’d met that would be Rowling, King, and maybe Dan Brown.
Edit: Oh wait, among the best regarded living, there’s also Tom Wolfe.
Franzen is considered an excellent craftsman - his sentences can gleam. But his novels don’t standout as works for the ages. His friend **David Foster Wallace ** would’ve been in the conversation if he was still alive. I love his work, even if I can’t fully plow through Infinite Jest 
Tom Wolfe is well-regarded as a gonzo journalist; not so much as an novelist past Bonfire, which wasn’t all that great in hindsight other than as contemporary satire. The Right Stuff is brilliant.
I have an irrational hatred of Jonathan Franzen that I probably need to let go. It’s my fault for reading a bunch of his essays, which made me want to punch him more than anything. And hear, hear re: Infinite Jest. Yeah, that’s been collecting dust on my bookshelf for about a year now. I’ll read it someday!
I have a lot of hate for Franzen - I find his arrogant satiric commentary on America, families, the Midwest, etc. to be frustrating, and his public “processing” of the death of his friend Wallace to be wrong-footed at times - commenting on DFW’s suicide in ways that offend DFW fans. His handling of Oprah-gate kinda exemplifies this.
However, I know a woman in NYC who manages a theater group - they did an experimental production of a play based on a Franzen essay - House for Sale. He showed up for a panel after one of the shows. I didn’t attend, but my friend said he was very, very different from the persona he portrays in his writing - nice, gracious, open to any questions and questioning of his intent, etc.
So - I respect his writing sentence by sentence, really don’t like his works, but was pleased to hear he wasn’t a big jerk in real life…
As with most of the other replies here, I’m inclined to agree Stephen King and JK Rowling are probably the best known living fiction authors, although I’m going to give an edge to King for being known for more than one writing “thing”; even though Rowling has done something(s) besides Harry Potter and the Multitudinous Sequels the vast majority of her work involves the titular boy wizard.
IMHO They’re both closely followed by people like Tom Clancy, Clive Cussler, Danielle Steele, Dan Brown and Wilbur Smith, who’ve all written so many books it’s a fairly safe bet most people have at least one of them on their bookshelves - or have, at some point, read one.*
As for best regarded - how about Frederick Forsyth? He’s widely regarded as a master story teller and his stories are meticulously researched and topical.
I did think about trying to answer the questions with regards to non-fiction authors but I think there’s likely to be too much disagreement over what qualifies as “best known” since a lot of authors might be very well known in their specific field but completely unknown outside it, whereas a lot of non-fiction authors are well-known even to people who don’t read that genre, IMHO.
*This is the point where most of the SDMB usually comes in to say they’ve never owned or read a book by those authors. I direct you to my signature in response.
I’d say it depends on what the OP means by “highly regarded”. If that’s “highly regarded by critics” or “won the most prestigious literary awards” then I agree that Rowling and King are out of the running. But if it’s just a matter of “the largest number of people would agree that this person is a good author” then that’s not going to be Nobel prize contenders but rather authors whose work is appealing to the broadest audience.
The answers so far seem to be leaning a lot more towards “most widely read” or perhaps “most anticipated next book” or just plain popularity, rather than “highly regarded.” IMVHO.
To qualify as “highly regarded,” I think you have to look past sheer popularity and at the level of both critical and reader respect the author is given. On that scale, Harper Lee and her one book would indeed score very highly.
I haven’t read those other guys but I used to devour Wilbur Smith’s books and I’m not ashamed to admit it. Same with Sidney Sheldon, Ken Follett and Frank Yerby. 
John Grisham is up there with King and Rowling in popularity.
“Highly regarded” means “critical praise” to me too – professional critics, not Amazon or Goodreads critics.
I have high regard for a lot of authors whose books I don’t care for. I recognize the literary quality but they don’t appeal to me.
By whom? Not by critics. He’s a popular author, but he’s not Hemingway by any stretch.
I assume best-regarded means held up by writers and respected critics and academics as at the top if the craft. When people get feisty about the obscurity of the Nobel - and then cite examples of critically-acclaimed writers who haven’t won yet? Those guys
King is a transcendent genre writer - so good at Horror that he is seen as a great writer, period. Elmore Leonard was the same for Crime, LeCarre for Espionage, etc. those writers are not held in the same regard as, say, Coetzee.
If you add boring/predictable to this, we’re on the same page.