Here are some of the following reasons that books are commonly challenged: insensitivity, gender roles, LGBT content, inaccuracy, profanity, supernatural forces, violence, dislike for the author, dangerous content, death, satanic rituals, violence, horror, racism, nudity, sexually explicit content, offensive language, religious viewpoints, political viewpoints, and drug references.
Some of the most frequenly challenged authors include Dav Pilkey, Sherman Alexie, Toni Morrison, John Green, Rudolfo Anaya, Stephen Chobsky, Suzanne Collins, Lisa McMann, Gary Paulsen, Jeff Smith, and Tanya Lee Stone.