I haven’t had it happen too often, but I stick with the author’s version. About the only time I noticed it was hearing Terry Brooks pronounce “Shannara.”
Chip Delany’s pronunciation of “Nevèrÿon” is also what I hadn’t expected. I hadn’t realized what he meant by the accents – it’s pronounced “Nuh-VAIR-ee-on.”
In Stephen King’s Dark Tower series, his character Roland often reminisces about his childhood friend Cuthbert. To me, it was always pronounced “Cuth-bert.”
In Wizard & Glass from that series, someone is referring to Cuthbert’s real name (part of the novel revolves around them having assumed false names…Cuthbert’s was “Arthur Heath.”), and pronounces it “Cuh-yooth-bert.”
Which now makes me wonder how Elisha Cuthbert pronounces her last name.
When I first read the name “Golan Trevize” in the Foundation series, I pronounced it with three syllables—Treh-vee-zay
At some point when another character calls him “Trev” he says that his name has two syllables “Trev-ize.”
I didn’t like the way that sounded so I stuck with my version.
Generally, I take the author’s intention, but there are a few times where I just don’t see it and insist on my own.
For example, there’s a Discworld character named “Teatime” and the book specifically tells you to pronounce it “Te-ah-time-ah” and I refuse to do that. (I suspect most readers do - it’s probably an intentional joke that way.)
I have also given up trying to pronounce Welsh names correctly. I’m sorry, but you people need to use the same letters in the same way as the rest of us. 
One reason I prefer to use the author’s pronunciation is that it’s often a good clue as to how other names are pronounced. For example, where you place the accent on Shannara should be a result of some consistent linguistic scheme that other names follow. I’m not familiar enough with those novels to know whether it is consistent or not. If it’s not consistent, then I’m likely to insist on my own pronunciation regardless of the author.
Who woulda thunk that you’re supposed to pronounce the K in Knufflebunny?
One that I’ve run across a lot are the names of European board games. We Americans apparently amuse the hell out of Europeans as we try to pronounce names like Agricola, Antike, Carcassonne, Caylus, Cyclades, Formula Dé, Le Havre, Strozzi, Sylla, Tannhäuser, Troyes, Tuchulcha, Yggdrasil, and Ys.
One more is comic book publisher Catherine Yronwode (or catherine yronwode). It took me a long time to find out her last name is pronounced Ironwood.
I have just finished the 3rd Harry Potter book.I have heard my stepdaughter pronounce the character Hermione’s name as Her-My-Knee many times. As of the ending of the 3rd book, there has never been an explicit pronunciation stated. So I flop back and forth between Her-Me-Own, which is how I guessed the pronunciation should be, and Her-My-Knee.
I don’t doubt my stepdaughter’s judgement, and she has seen the movies, but until I myself am directed by either the author or the story, I will waffle.
In one of the books, bobot, Viktor Krum pronounces it “Her-My-Knee.” And, IIRC, she corrects his pronunciation. Had a friend who actually named his daughter Hermione.
Apparently it’s a not-entirely uncommon British name, and they pronounce it Her-MY-uh-knee. That’s how it’s pronounced in the movies, and by JK Rowling in interviews.
In Jacqueline Lichtenberg’s House of Zeor, one of the main characters is named Klyd. I first read the book in junior high, and for many years I pronounced it “Klid.” According to the author, it’s actually pronounced like “Clyde.”
I can’t bring myself to do that, though. The character is really cool and my favorite in the series, and to me the name “Clyde,” no matter how it’s spelled, has connotations of redneck guys with missing teeth (no offense to any Dopers named Clyde–it’s my issue, not yours). So he’s always gonna be “Klid” to me.
I thought he called her “Her-mee-own,” and “Herm-oh-ninny.” 
Ditto.
Absolutely it’s an intentional joke. WC Fields in THE BANK DICK plays Egbert Sousè and constantly says, “Sou-say, with an accent aigu over the e”
You’re probably right. It’s been a while since I’ve read them, and I don’t have them handy to check. I did remember the pronunciation that bobot being in the book, though.
The “real” Tolkein pronunciations were lost on me when I first read his stuff in high school. When I read explanations of how they were truly pronounced, it still wasn’t “real” in my head, not until the movies created an annoying dissonance after I actually heard it. So, I still tend to read the dragon’s name in my head as “Smawg,” not “Smowg.” But I don’t bother with Gandalf, because my mispronunciation is close enough.
I had a high-school drama teacher correct me, but darned if I didn’t prefer “Waiting for Gho-Dott.”
If it was spelled “Shanarra” I think the incorrect-but-popular pronunciation would be correct. The actual spelling is “Shannara,” so it’s not wrong to pronounce it Terry Brooks’s chosen way, but I think both pronunciations are still reasonable with that spelling.
I will always switch to the author’s way. The author knows best. This has happened a lot with George Martin’s books since Game of Thrones began airing.
Martin has explicitly disavowed any expertise on knowing how the names of his characters should be pronounced. He has said in interviews that he knows nothing about such linguistic matters and trusts the TV producers to come up with the correct pronunciations.
Still, I’ve adopted the show’s style.