We all know the great thing about literature is its power to transport you to another world. Authors have the freedom to create these imaginary characters, settings and situations that can enlighten, entertain and engage readers.

However, when you're able to write whatever you want, not everyone is going to be a fan of your work. Some people might not only dislike certain novels, but they also might find them so objectionable, that they "challenge" them and file a complaint to the American Library Association's Office for Intellectual Freedom to have them removed from libraries and schools. When individuals or people are successful at getting books removed, then they fall under the banner of "Banned Books."

Since 1982, the American Library Association has celebrated Banned Books Week to highlight the most frequently challenged and banned books in the country and promote freedom of expression. The organization releases a list of the most challenged books every year, and each list usually contains seemingly harmless books that make you wonder why anyone would challenge them. When the books were released, was there any inclination that they would be controversial? Looking at The New York Times reviews of some of the most frequently challenged books of the 21st century may give us some insight into whether or not there was any sort of hint that some might find these books objectionable.

1. The Harry Potter series by J.K. Rowling

Though Harry Potter is one of the most-beloved book series of all time, it has been challenged for featuring the occult/Satanism, violence and for being anti-family. Of course, the books get much darker as the series goes on, but people have been challenging the book since it first debuted in the U.S. with Harry Potter and the Sorcerer's Stone. Though Michael Winerip's Feb. 14, 1999 New York Times review of the first book in the series is obviously filled with fantastical descriptions of all of the magic in the book, it mostly describes how fun it is. "This is a terrific person we'd love to have for a best friend," Winerip referred to Harry in his review. We get the sense that this is a special book but not one that would inspire so much anger in people. 

2. Scary Stories series by Alvin Schwartz

When you write a series of books meant to scare the living daylights out of children, you probably have a feeling that they might not go over so well with some people. That is the case for Alvin Schwartz's Scary Stories series, which has been challenged for not being suitable for the age group due to the violence and the occult/Satanism featured in the work. Merri Rosenberg's Jan. 17, 1982 New York Times review of Schwartz's first book in the series, Scary Stories to Tell in the Dark, indicated that this book might not be appropriate for children. "These stories are the stuff nightmares are made of, and I'd suspect they're almost too effective for sensitive youngsters," Rosenberg wrote.

3. Of Mice and Men by John Steinbeck

Ralph Thompson had nothing but praise when he reviewed John Steinbeck's Depression-era classic for The New York Times. The book has been challenged for offensive language, racism and violence, the latter of which Thompson gives a hint of in his review, describing the scene where George throws the mouse Lennie found into a bush. Overall, Thompson wrote that the book is "strong, moving and very funny," which indicates that it would probably be an enjoyable read for most people.

4. I Know Why the Caged Bird Sings by Maya Angelou

Christopher Lehmann-Haupt called Maya Angelou's I Know Why the Caged Bird Sings "a carefully wrought, simultaneously touching and comic memoir of a black girl's slow and clumsy growth." That one sentence hints at a coming-of-age tale that features the author exploring her racial, sexual and personal identity. Angelou's book has been challenged for offensive language, sexually explicit content and not being suitable for an age group. There is probably some validity to these statements, but real life is messy sometimes.

5. And Tango Makes Three by Justin Richardson and Peter Parnell

And Tango Makes Three was most likely challenged for homosexuality, its religious viewpoint and its anti-family message because it is a children's book based on the true story of two Central Park Zoo male penguins raising a chick. Sarah Weeks acknowledged that the book was "bound to raise eyebrows," but she also noted that "for those of us eager to encourage our children to include, rather than exclude, it's a welcome addition to the library of families." Apparently, not everyone felt that way.  

6. His Dark Materials series by Philip Pullman

Philip Pullman's His Dark Materials series has been challenged for its religious and political viewpoints, as well as violence. Gregory Maguire's New York Times review of the second book of the series, The Subtle Knife, on April 19, 1998 describes many of the mystical happenings readers can find in the novel and also lists many unpleasant instances, such as shoot-outs, break-ins and torture, so it's not surprising that some people took issue with this series. 

7. Fallen Angels by Walter Dean Myers

From the beginning of Mel Watkins' Jan. 22, 1989 review of Fallen Angels, he acknowledges that Walter Dean Myers' Vietnam War-set novel is "graphic" and "evokes the tension, anxiety and fear that grip the recruits." So it's not a surprise that the book would be challenged for violence, racism and drug use. 

8. It's Perfectly Normal by Robie H. Harris

Since It's Perfectly Normal is a book about puberty, it's not shocking that the book would be challenged for nudity and sex education. Still, The New York Times' Besty Hearne noted that "the cartoon illustrations extend its appeal to readers in a remarkably broad age range even though the book is intended for early adolescents."  

9. Captain Underpants series by Dav Pilkey

This series is filled with so much adolescent humor, it's strange that it has been challenged for being unsuitable to any age group for its violence and sexually explicit content. Still, The New York Times review of Pilkey's second book in the series, Captain Underpants and the Attack of the Talking Toilets, acknowledges that the book is basically all potty humor.

10. The Bluest Eye by Toni Morrison

Toni Morrison's The Bluest Eye has been challenged for its offensive language, violence and sexually explicit content. John Leonard's review of the book discusses how it challenges commonly-held notions of beauty in the U.S., which makes the book inherently controversial.