"Censorship ends in logical completeness when nobody is allowed to read any books except the books that nobody reads." -- George Bernard Shaw
It is fairly common knowledge that some of the best books seem to attract the most bannings. Below is a list of some of the best children's and young adult books which are commonly or have been banned, along with the given reasons for their banning.
The Adventures of Huckleberry Finn (Bantam Classic) by Mark Twain, which is usually among the top ten books banned from highschools in the U.S. due to the use of racial slurs. It should be known that Twain used the slurs because that is what the characters would do, but personally was not racist. The characters' development leads them to change their ways somewhat as well.
The Catcher in the Rye by J. D. Salinger is also a very common banning in U.S. public schools, while simultaneously being one of the most commonly required for reading. The general issues are that the character engages in immoral behavior and for curse words used in the book. Censors fail to realize that it is his moral void that is the essence of the book.
The Chocolate War by Robert Cormier is frequently challenged simply on the basis of being somewhat nihilistic to some readers. Other reasons are the use of curse words and sexuality.
Flowers for Algernon by Daniel Keyes is a highly regarded banned book, although I personally didn't like it too much when I read it in middle school. School boards have banned it for sexuality and alcohol use.
Fahrenheit 451 by Ray Bradbury, ironically considering the content of the book, has been banned for being "socialistic" and for curse words.
Hatchet by Gary Paulsen is a junior high-level book. Reasons for banning it have been descriptions of injuries and trauma that were apparently too well written.
Harry Potter Hard Cover Boxed Set: Books #1-7 by J. K. Rowling have been banned widely for themes of witchcraft, supposedly tied to Satanism despite that only Christian holidays are celebrated or even mentioned in the books, and sometimes for the themes of challenging authority. One censor complained that it "made magic and witchcraft alluring" to children.
The Lorax (Classic Seuss) by Dr. Seuss, banned in some U.S. areas for, and I quote, "being an allegorical political commentary". Yes, that's an (pretty basic) analysis; what's wrong with that!
1984 (Signet Classics) by George Orwell, was banned in some parts of Florida, my own home state, for supposedly supporting communism and for supporting sexuality. Another ironic banning.
Of Mice and Men by John Steinbeck has been banned in some high schools in the U.S. for profanity and also supposedly supporting euthanasia.
Speak by Laurie Halse Anderson, has been banned from some middle and high schools for sexuality, situations of suicidal thoughts in teens, and gritty teenage situations; it seems teens should only be allowed to actually deal with these issues, not ever read about them and potentially get a greater understanding or solace in shared experiences.
What My Mother Doesn't Know by Sonya Sones, is usually listed as challenged for sexuality-related content and teen issues; one of the most banned of 2005.
Anne Frank: The Diary of a Young Girl by Anne Frank for being too depressing for students; sheesh, she shouldn't have let her imagination run away with her on the details, eh, stuck more to real life.
Blubber by Judy Blume is criticized for having immoral characters who go unpunished and for curse words. Many of Blume's books have been banned, often for sexuality issues.
Bony-Legs by Joanna Cole, for magic and witchcraft. The witch is actually evil in this one, though.
Harriet the Spy by Louise Fitzhugh for the apparent poor influence it will have on children which is anti-authoritative; it just won't do for the little minions to think outside the box.
A Light in the Attic by Shel Silverstein, apparently for a single poem and accompanying illustration which suggests that children could avoid washing dishes by breaking them.
Sylvester and the Magic Pebble (Stories to Go!) by William Steig, for a quite ridiculous reason, possibly the most ridiculous of all these: the depiction of the characters as animals, particularly the police as pigs, apparently upset people.
The American Heritage Dictionary of the English Language, Fourth Edition is one of my favorite cases, although not exactly a kids book; it was banned in some libraries for containing "39 objectionable words" such as slang terms "bed" "knocker" and "balls". I wonder what Orwell would think of banning the Dictionary, but he's banned, too, so no one will wonder.
Forever by Judy Blume is another Blume book commonly banned. The reasons are teen sexuality and relationship issues. Deenie by Blume is commonly banned as well, for similar reasons.
The Pigman by Paul Zindel has been challenged for containing curse words, sensuality, and for teen mischief and anti-authoritarianism at school.
Where the Sidewalk Ends: Poems and Drawings by Shel Silverstein has been banned because the poem "Ladies First" apparently supports cannibalism; I would have never even thought of this, considering that the cannabilistic king is portrayed as evil in that he will be eating the narrator.
The Lion, the Witch and the Wardrobe (The Chronicles of Narnia) by C.S. Lewis, which I suspect is most frequently banned because of the term "witch" in the title by overzealous Christians; not that the banning would be okay otherwise, but Lewis was a deeply devoted Christian scholar, so calling his works unchristian is kind of ridiculous (of course though!).
Bridge to Terabithia by Katherine Paterson, one of the best books I read in my childhood, has been banned for grief, swear words, and suggestions of witchcraft.
A Day No Pigs Would Die by Robert Newton Peck has been banned for a scene depicting pig breeding and also for a gory scene.
Sounder by William H. Armstrong has been challenged for use of a racial slur.
The Indian in the Cupboard by Lynne Reid Banks was challenged for containing mild curse words and suggestions of racial stereotypes.
Julie of the Wolves (HarperClassics) by Jean Craighead George has been frequently challenged for contents of violent sexuality, profanity, and supposed socialistic, evolutionist, and "anti-family" themes.
James and the Giant Peach by Roald Dahl, one of my favorite books of all time, has been challenged for containing mild profanity and depicting positive anti-authority behavior and cruel aunts.
A Wrinkle in Time (Time Quintet) by Madeline L'Engle, which has been frequently challenged for support of occultist religions and acts and apparently not being Christian enough.
The Giving Tree by Shel Silverstein, which some apparently considered sexist.
The Giver (Giver Quartet) by Lois Lowry has been banned from middle schools for supporting sexuality and for scenes of violence.
"The Elephant's Child", part of Just So Stories by Rudyard Kipling, has been banned for being "99 percent violent".
The First Captain Underpants Collection (Books 1-4) by Dav Pilkey have been challenged for the diaper and poo themed superheroes. They are tremendously fun books. It may just be the revenge of teachers who told Pilkey as a student that he would never be a good artist or author.
Dangerously Alice and the rest of the Alice series by Phyllis Reynolds Naylor have been one of the most common challenged books due to realistic depiction of teen issues growing up and particularly discussion of sexuality and relationships.