20 Things You Didn't Know About Batman

1. Though Bob Kane is credited with the creation of the Batman character, his right-hand man Bill Finger actually came up with the idea. Kane often relied on Finger to do most of the work and never received credit. Eventually, Finger left Kane's employment and worked for DC Comics directly and created characters like the Green Lantern.
2. Batman debuted in 1939, but key elements of his mythos came later. The city of Gotham City was introduced in 1940 (with Batman having previously lived in Superman's Metropolis or just New York City), the Bat-Signal didn't come until 1942, and the Batcave finally made its first appearance in 1948.
3. While Batman is known for never killing anyone or using firearms, the character did both in his early years.
4. Robin was originally supposed to be a one-time character, but his debut issue in 1940 sold double what a typical issue sold, so they kept Robin around.
5. Batgirl was created specifically for the 1960s TV show. Producers requested that the comic books come up with a female counterpart to the Caped Crusader, who they could then use in the show, which was in dire need of a ratings boost. The character appeared in both mediums in 1967. Her popularity on the TV show was impressive enough to almost get her a spin-off series, but couldn't save the show itself. It was canceled in 1978.
6. In 2012, Forbes estimated Bruce Wayne's fortune at $6.9 billion, making him the eighth richest fictional character.
7. In the 1950s and 60s, Batman stories shifted from a dark, violent tone to a lighter one that many called "camp" and associated with gay culture, a theory propelled in 1954 by psychiatrist Fredric Wertham, who often protested comics and the effects of mass media on children.
8. Before Michael Keaton was cast as the lead in Tim Burton's Batman, the direction and Warner Bros. had considered Alec Baldwin, Mel Gibson, Kevin Costner, Charlie Sheen, Pierce Brosnan, Tom Selleck, and Bill Murray for the role.
9. Sean Young was originally cast as Vicki Vale in Batman but was forced to pull out after breaking her arm one week before filming. The actress auditioned for the role of Catwoman in the sequel, Batman Returns, and even wore a homemade costume on various talk shows to campaign for the role. Thankfully, it didn't work and Michelle Pfeiffer was cast.
10. Prince was contracted to write two songs for Batman, but loved the film so much that he wrote an entire soundtrack, which was eventually scrapped altogether.
11. Robin Williams turned down the role of the Riddler in Batman Forever because he felt it wasn't funny enough. The role eventually went to Jim Carrey.
12. After Batman & Robin was panned by critics and was financially unsatisfying, Warner Bros. scrapped a fifth film that would have featured the Scarecrow and Harley Quinn as its villains. Instead, they developed several other proposals to continue the franchise, including a prequel, a live-action film based on the animated series Batman Beyond, and a Batman vs. Superman film, which will manifest itself in the 2015 Man of Steel sequel.
13. Batman: the Animated Series not only established the long-running DC Animated Universe, which included several other series like Superman, Batman Beyond, and Justice League, but also won an Emmy and created characters like Harley Quinn that later became staples in the comics.
14. For Batman Begins, the Gotham City license plates were made to look like Illinois plates so they would blend in during car chases scenes filmed in Chicago.
15. When The Dark Knight was delivered to theaters, it was titled Oliver's Army to deter piracy.
16. Heath Ledger locked himself in a hotel room for a month one to prepare for his role as the Joker in The Dark Knight. The one thing he didn't initially plan as part of the character's psychotic idiosyncrasy was the constant licking of his lips and cheeks, which he did out of discomfort with the prosthetic make-up.
17. Warner Bros. originally wanted Leonardo DiCaprio to play the Riddler in The Dark Knight Rises, before Christopher Nolan opted to use Bane and Catwoman as the villains. Leonardo was also considered for the role of Robin in Batman Forever but was beat out by Chris O'Donnell.
18. Mr. Freeze was originally a comedic villain until Batman: the Animated Series created a tragic backstory in which his motivation is to save his cryogenically frozen wife, who suffers from a rare disease.
19. Poison Ivy, initially a supporting villain, was promoted throughout the 1970s and 80s in response to the feminist argument that comic books needed more female characters. The continued characterization of Catwoman as sympathetic left room for Poison Ivy to be Batman's primary female antagonist.
20. Though many Batman characters have inconsistent backstories and portrayals, none are as polarizing as the Penguin, who is sometimes portrayed as a grotesque and deformed outcast, and other times as a high-profile aristocrat.