I thought I'd offer this selection of my favorite authors. Make of it what you will, and no, having seen a movie adaptation doesn't count!
I've read all his Hitchiker's Guide to the Galaxy books. At his best the guys is hilarious. At his worst he's still a very polished writer.
I've read Empire of the Sun and Crash, both of which inspired movies of the same names. He writes (wrote?) with an intensity that few authors can surpass, while at the same time using themes and subject matter that other writers wouldn't touch.
Jose Luis Borges
Like the South American answer to H. P. Lovecraft, Borges was a quiet, extremely literate man who wrote some of the strangest stories ever. All of his fiction can be found in a single volume.
Arthur C. Clarke
I've read all of his 2001 series, Childhood's End, and several of his short stories. I have no doubt that some of his later work was astonishingly dull, but his early work is science fiction at its best.
There's a lot more to this guy than Heart of Darkness. He was also one of the most adventurous, most experimental writers ever. My favorite of his books is probably Nostromo. Who else could write a two page long description of the sun setting upon the ocean, and make you sorry that it was only two pages long?
Philip K. Dick
I've read, I think, over 20 of his novels. The V.A.L.I.S. Trilogy, A Scanner Darkly, and the Transmigration of Timothy Archer are all classic. He was a brilliant, paranoid, emotionally disturbed man who wrote some excellent books.
Early Dickens is what you want to read first. Oliver Twist, Great Expectations - all of that. His later books, while good, amplify the social commentary at the expense of his sense of humor. I've read a lot of his books - maybe more than 10 now - but Oliver Twist remains my favorite.
Dumas is one of the great French authors, having penned (at least part of) The Three Musketeers, The Count of Monte Cristo, and The Man in the Iron Mask. His books aren't just great adventure stories. They're also quite funny.
Ellroy the writer a lot like many of his characters. He finds something that works, and then proceeds to beat it to death. His L.A. Quartet and Underworld USA Trilogy are all excellent books full of sex and violence.
The archetypal Southern writer, Faulkner was a functioning alcoholic who wrote sprawling sagas about Southern towns, Southern families, and Southern life. Go Down, Moses is probably my favorite of his books, though if he ever wrote a bad book I've yet to read it.
If you ever want to read something tortured, I'd highly recommend The End of the Affair. I've also read Journey Without Maps and The Quiet American, both of which were great.
Yes, he wrote some bad books, but his best books are imaginative works that will stand the test of time. I've read his entire bibliography, and I highly recommend God Emperor of Dune, The Jesus Incident (written with Bill Ransom), and The Godmakers.
I believe I've read all of his fiction. The Jungle Book and his other writings are good, but Kim blows them all out of the water. Kipling had a lot to say about the British Empire, and man's relationship with the natural world.
An awkward, sickly New Englander who worshiped another awkward, sickly New Englander by the name of Edgar Allan Poe. Not everything Lovecraft wrote was good - some of it was derivative, some of it was also racist - but no one re-imagined other dimensions, ancient cults, and bizarre, galaxy-spanning horrors with greater skill. At the Mountains of Madness is probably his best story.
Gabriel Marcia Marquez
Undoubtedly my favorite South American writer, and I've read books by quite a few South American writers. 100 Years of Solitude is one of my favorite books, and Love in the Time of Cholera is also very good.
George R. R. Martin
Everyone fawning over the Game of Thrones TV series really ought to read the books. How Martin writes such long, complicated, morally ambiguous books is beyond me, but I'm glad that he does. I'm very much looking forward to his next novel.
Something of a latter-day Faulkner, but McCarthy writes in a style that is very much his own. I cannot praise his Border Trilogy enough, and he continues to impress me with both the quality of his writing and the erudition necessary to flesh out his plots. There is also a lot of depravity in his novels, and I enjoy that.
Moby Dick might still be the quintessential American novel. It remains my favorite of his books, though Melville's other books are sadly overlooked. His first book, Typee, is also very good, as are some of his later, more experimental works.
Edgar Allan Poe
Like Melville and Hawthorne, Poe was one of the first great American writers. His style of writing was at once more verbose and more conventional than either of those writers, and he is sometimes credited with inventing both the detective and science fiction genres. Like his acolyte Lovecraft, he's had more than one reader pulling out the dictionary.
Roth has received a lot of attention within the past decade or so, but his earlier works, much like those of Cormac McCarthy, were largely overlooked when they were first published. His books can be extremely depressing, and his fiction has a masturbatory side that grows tiresome, but even so he's written some great books. American Pastoral is my favorite.
Verne is another famous Frenchman, and he may have also invented the science fiction genre. His characters are paper-thin, his plots are ridiculous, but no one wrote an adventure story like Verne. I recommend starting from his more famous books and branching outward from there.