A - L: Adams, Richard. Watership Down; Ships Cat (&c); Alcott, Lousia May. Little Woman; Good Wives; Little Men; Jo's Boys (&c&c); Angeli, Marguerite de. The Door in the Wall; Austen, Jane. Sense and Sensibility; Pride and Prejudice (&c); Barrie, J.M. Peter Pan; Baum, Frank. L. The Wizard of Oz (&c&c); Beagle, Peter S. The Last Unicorn (&c); Bemelmans, Ludwig. Madeleine; Madeleine's Rescue (&c &c); Bianco, Margary Williams. The Velveteen Rabbit; Blume, Judy. Tales of a Fourth Grade Nothing; Are You There God, It's Me Margaret (&c); Bond, Michael A Bear Called Paddington (&c); Bronte, Charlotte. Jane Eyre; Burnett, Frances Hodgson. The Secret Garden; The Little Princess; Carroll, Lewis. Alice in Wonderland; Christie, Agatha Ten Little Indians (&c); Cleary, Beverley. Runaway Ralph; Ramona (&c&c); Coolidge, Susan What Katy Did (&c); Dahl, Ronald. Charlie & the Chocolate Factory; James & the Giant Peach (&c); Dickens, Charles. A Christmas Carol (&c); Doyle, AConan, The Hound of the Baskervilles; Dubois, William Pene. The Twenty-One Balloons; Estes, Eleanor. The Middle Moffat (&c); Farley, Walter. The Black Stallion; The Island Stallion (&c &c); Fitzhugh, Louise. Harriet the Spy (&c &c); Frank, Anne. The Diary of a Young Girl; Graham, Kenneth. The Wind in the Willows; Henry, Marguerite. King of the Wind ; Hilton, James. Goodbye, Mr. Chips; Irving, Washington, The Legend of Sleepy Hollow; Kipling, Rudyard. Just So Stories; King-smith, Dick. Pigs Might Fly; Knowles, John. A Separate Peace; Langton, Jane. The Diamond in the Window (&c); Lee, Harper. To Kill a Mockingbird; L'Engle, Madeleine. A Wrinkle in Time; Swiftly Tilting Planet (&c) ; Lewis, C. S. The Chronicles of Narnia (&c&c); Lindgren, Astrid. Pippi Longstocking (&c); London, Jack. The Call of the Wild; Lowry, Lois. Number the Stars; Jacques, Brian. Redwall; Creech, Susan. Walk Two Moons; Handler, Daniel as Lemony Snicket. A Series of Unfortunate Events; Golding, William. Lord of the Flies; Dickens, Charles. Oliver Twist. A Tale of Two Cities. A Christmas Carol.
M - Z: Macdonald, George. The Back of the North Wind; McKinley, Robin. The Hero and the Crown; Miller, Walter M. A Canticle for Leibowitz; Milne, A.A. Winnie the Pooh; Montgomery, LM Ann of Green Gables (&c); O'Brien, Robert C. Mrs Frisby and Rats of Nimh; Odell, Scott. Island of the Blue Dolphin; Sing Down the Moon (&c); Otis, James. Toby Tyler; Or Ten Weeks with the Circus; Norton, Mary. The Borrowers; Paterson, Katherine. The Bridge of Terabithia ; Rawls, Wilson, Where the Red Fern Grows; Rowling, J. K. The Harry Potter series; St. Exupery, Antoine. The Little Prince; Sewell, Anna. Black Beauty. Sendak, Marurice, where the Wild Things Are, In the Night Kitchen (&c &c); Seuss, Dr. Horton Hears a Who; Silverstein, Shel. Where the Sidewalk Ends; The Light in the Attic; The Giving Tree; Smith, Dodie. The Hundred and One Dalmatians; I Capture the Castle (&c); Spyri, Johanna. Heidi; Steinbeck, John. The Pearl; Stevenson, R.L. Treasure Island; Kidnapped (&c); Stewart, Mary The Crystal Cave; The Hollow Hills; The Last Enchantment (&c); Streatfield, Noel. The Magic Summer; Sutton, Margaret. Judy Bolton books; Tarkington, Booth. Penrod; Penrod and Sam; Tolkien, JR. The Hobbit; The Fellowship of the Ring; Travers, PL. Mary Poppins; Comes Back; & the West Wind; in the Park; Viorst, Judith. the Tenth Good Thing About Barney; My Mama says there aren't any... &c&c); White, E. B. The Trumpet of the Swan; Charlotte's Web; Stuart Little; White, T. H. The Once and Future King; Wilder, Laura Inghills. The Little House on the Prairie (&c &c); Wright, Richard. Black Boy; Wyss, Johann David. The Swiss Family Robinson; Kay Thompson and Hilary Knight, Eloisa books; Weisel, Elie. Night; Nazario, Sonia. Enrique's Journey; Tolkien. The Fellowship of the Ring and The Hobbit; Santiago, Esmeralda. When I was Puerto Rican; Rushdie, Salman. Haroun and the Sea of Stories; Dr Seuss books; Pierce, Tamora. The Alanna books.
Anonymous (very prolific):
Go Ask Alice; Nancy Drew, Hardy Boys, Star Trek/Star Wars. Most series books are written by syndicates, originally there may have been an author who conceived the characters and a story, but most of the time the books are then rewritten and updated every couple of decades (or nowadays sooner) according to a standard formula. Sometimes even the original book is a concoction of a commercial syndicate.