Origin of Joker
While the Hollywood films of 'Batman', 'Suicide Squad' and 'Joker' have made the character of Joker famous over the years, not many apart from the fans may know that the character for the supervillain was created by Bill Finger, Bob Kane and Jerry Robinson, for DC Comics. He also appeared in the first ever issue of Batman on April 25, 1940. However, the credit for who created it is often in contention, as Kane and Robinson say they designed him while Finger had contributed with his writing.

Becoming the archenemesis 
It is said that Joker was going to be killed off during his initial introduction but continued to feature after some editorial intervention. While he does not have any superhuman abilities, he is one of the few villains who doesn't have an origin story, as there are multiple storylines that have been explored over the years. One of the most popular ones is how he fell into a tank of chemical waste that eventually gave him the signature appearance of green hair with the white face and bright red lips. However, he is known to be a psychopath with a need to create chaos, and does that with the help of his knowledge in chemical engineering.

Rise and fall and rise of Joker
Initially, he appeared as a jewel thief and serial killer before he finding his origin story in 1951 after Finger wrote it for Detective Comics #168. However, the character started appearing less frequently after 1964 because Julius Schwartz, who was the editor, is said to have disliked him. However, the 1966 Batman television series changed things. The series saw Cesar Romero play Joker, and the show revived an interest in the supervillain and him featuring in the comic books. In what is called as the Gold Age, Joker was one of the few villains to appear in the Batman comics in the Silver Age. Unfortunately, after the series ended in 1969, the interest disappeared but was revived in 1973 by writer Dennis O'Neil and artist Neal Adams, in Batman #251's 'The Joker's Five-Way Revenge'. In 1975, Joker became the first villain to feature as the title character in the comic book series, The Joker.

Reservations on the character 
Interestingly, the appearance and disappearance of the character was not the only effect Joker had. At one point, German-American psychiatrist and author Frederic Wertham believed that mass media like comic books led to a rise in juvenile delinquency, violence, and homosexuality in young males. This led to the formation of Comics Code Authority in 1954 in the US to self-regulate their content. It ended up banning gore, innuendo and excessive violence leading to a Batman without menace, and the Joker without his homicidal side and instead into a funny thief and trickster. 

Movies with Joker
With this change, The Joker comic book series ended very early on. However, fortunes changed when American comic book editor Jenette Kahn became the editor of DC Comics, leading to Joker becoming one of the most popular characters during her time. While O'Neil and Adams made the character popular, writer Steve Englehart and penciller Marshall Rogers's work on the villain led to the future that started with the 1989 Batman film, and their series led to the 1992 Batman: The Animated Series, which also introduced Joker's sidekick Harley Quinn. Even before the 1989 movie, Joker featured in the 1966 Batman movie, and after that in the 2008 film The Dark Knight, where he was played by Heath Ledger, who made him popular. He also appeared in the 2016 film Suicide Squad, where the character was played by Jared Leto, followed by the titular movies of Joker (2019) played by Joaquin Phoenix, and again in 2024 in Joker: Folie a Deux'.