Underground comix are small press or self-published comic books that are often socially relevant or satirical in nature. They differ from mainstream comics in depicting content forbidden to mainstream publications by the Comics Code Authority, including explicit drug use, sexuality, and violence. They were most popular in the United States in the late 1960s and 1970s, and in the United Kingdom in the 1970s.

Tijuana bibles were palm-sized erotic comics produced in the United States from the 1920s to the early 1960s. Their popularity peaked during the Great Depression era.