The Joker is a fictional super villain created by bill finger, Bob Kane and Jerry Robinson. They first appeared in the first issue of DC Comics' comic Batman (April 25, 1940). The credibility of clown writing has been disputed; Kane and Robinson claim responsibility for Joker's design, while acknowledging finger's writing contribution. Although originally intended to stand out among the clowns, he was spared by the editor's intervention, making the character tolerable as the enemy of the superhero Batman.

In his comic book, the clown is portrayed as a crime planner. Introduced as a psychopath with a perverse, sadistic sense of humor, the character became a silly prank in the late 1950s in response to the comics Code Commission's controls, and then recovered his dark roots in the early 1970s. As Batman's arch enemy, clowns have become part of the superhero definition story, including the murder of Robin and Batman's second ward, Jason Todd, and the paralysis of one of Batman's allies, Barbara Gordon. In the decades when he appeared, clowns had all kinds of possible origin stories. The most common story is that he fell into a can of chemical waste, which made his skin white, his hair green and his lips red. The disfigurement drove him mad. Batman is opposite to Batman in character and appearance. Critics think clown is his perfect match.

Instead of superhuman abilities, clowns use their expertise in chemical engineering to develop toxic or deadly compounds, as well as themed weapons, including razor tip poker, deadly buzzers and acid spray lapels. Clowns sometimes work with other Gotham City Super Villains (such as penguins and two sides) as well as groups such as unfair gangs and unfair alliances, but these relationships often break down because clowns want unrestricted chaos. In the 1990s, Harley Quinn, the clown's former psychiatrist, attracted romantic interest, and the latter became his villain. Although his main hobby is Batman, the clown also fights with other heroes, including Superman and magic woman.

The clown is one of the most iconic characters in the mass culture, known as the greatest comic villain and fictional character in history. The popularity of the character has made him appear in a wide range of goods, such as clothing and collections, inspired the structure of the real world (such as theme park attractions) and has been cited in many media. Clowns are adapted into real people, animated and video game avatars of Batman rivals, including the 1960s Batman TV series (played by Cesar Romero) and Jack Nicholson's Batman films (1989), Heath Ledger's "dark riders" (2008) and "suicide squad" Jared Leto (2016). Mark Hamill, Troy Baker and others provide the voice of the character.