Happy Batman Day, everyone! Around the world, May 1st may mark a spring holiday, but here, it marks the first appearance of the Dark Knight, in Detective Comics No. 27, in 1939.

For the past 76 years, the Caped Crusader has been fighting Gotham City evildoers in comic books, movies, TV shows, and pretty much anywhere else you can shine a Bat-signal. Throughout the years, Bruce Wayne's alter ego has gone through many incarnations, not just in actors (from Adam West to Michael Keaton to Christian Bale to Ben Affleck, among the many), but also in character, from haunted avenger to squeaky-clean do-gooder to campy clown to kinky prowler to world-weary fighter. He's due for yet another change this week, with the releases of DC's Batman No. 40 -- in which Bruce Wayne and the Joker finally kill each other (or do they?) and a special issue of DC's Divergence, where an undisclosed character takes up Bruce Wayne's mantle and becomes a new Batman in a heavily armored, RoboCop-like getup.

As familiar as we've all become with Batman over the years, there's still plenty you may not know about the character. (Indeed, DC and Warner Bros. are banking on it, hoping the mystery will draw you to see Affleck in next year's "Batman v. Superman: Dawn of Justice.") Here, then, are 25 things you didn't know about your favorite masked vigilante.

1. Bruce Wayne is named after Scottish hero Robert the Bruce and American Revolutionary hero Mad Anthony Wayne (who turns out to be an ancestor of Batman's, according to the comics).

2. The initial Batman stories were especially violent. Batman had no compunction about carrying a gun or killing his foes. Only later did Batman develop a code in which he refused to do either of those things, lest he sink to the level of the man who killed his parents.

3. Robin didn't show up until issue No 38. The young sidekick was the alter ego of Dick Grayson, part of a family of circus acrobats whose parents died in a high-wire accident. (It turned out that they'd been killed by mobsters who were shaking down the circus owner for protection money.) Naturally, Bruce Wayne identified with Dick's plight and adopted him as his ward.

4. There have been several Robins since, including Jason Todd, Tim Drake, Stephanie Brown, and Damian Wayne (Bruce Wayne's son by Talia al Ghul).

5. Batman's first screen appearance was in a 1943 serial called "The Batman." It starred Lewis Wilson as Batman and Douglas Croft as Robin. Made at the height of World War II, the shorts featured as their villain a Japanese spy named Dr. Daka, played in yellowface by J. Carroll Naish. The series wasn't very good, though it did introduce the concept of the Batcave. It also introduced a thin version of Alfred the Butler, who was then drawn skinnier in the comics.

6. Another serial a few years later, 1949's "Batman and Robin," starring Robert Lowery and Johnny Duncan, was better. It had the Dynamic Duo facing off against a black-hooded mastermind called The Wizard.

7. Were Batman and Robin gay? That was the insinuation of Dr. Fredric Wertham, whose 1954 book "Seduction of the innocent" became a best-seller with its claim that comic books were contributing to a nationwide epidemic of juvenile delinquency. He denounced comics for their grim tone and sensationalist violence, and he singled out Batman comics in particular for centering on a rich playboy who wore tights and went out swinging at night with his teenage ward. The book led to Congressional hearings, which in turn led to the creation of the Comics Code Authority, the industry's self-censorship operation. To earn the CCA seal and be sold in stores, comic books had to tone down the violence and sexuality, and heroes became more overtly positive role models. DC characters like Superman and Batman became virtual boy scouts. With more sordid underworld and occult tales off-limits, Batman and Robin soon found themselves entangling with space aliens and other bizarre, sci-fi monsters.

8. The 1966-68 "Batman" TV series starring Adam West as Bruce Wayne and Burt Ward as Dick Grayson brought some of the kink back, but strictly as camp, so arch that it went over the heads of the children who were the show's target audience.(Watch the reruns now, as a grown-up -- IFC has been running them every weekend -- and you'll guffaw at how much they got away with.) Hardcore Bat-fans hated the campy silliness, but the show did revive the DC comic's flagging sales.

9. In one series of Batman comics, Bruce Wayne married Catwoman. Their daughter Helena Wayne grew up to be the Huntress.

10. Frank Miller is generally credited with restoring Batman to his old gritty self with "The Dark Knight Returns," a four-issue series published in1986, where an aged Batman comes out of retirement, joined by a new Robin, to clean up the streets of a Gotham run amok.

11.Tim Burton's 1989 "Batman" became the first modern comic book blockbuster, cited for its dark tone borrowed from Miller. Before the film's release, fans were skeptical that Michael Keaton, the comic actor from Burton's "Beetlejuice," would make a credible Batman, but he proved more than capable of playing a Bruce Wayne still tormented by childhood trauma.

12. Among those actors Warner Bros. considered for the lead role were Kevin Costner, Mel Gibson, Bill Murray, Tom Selleck, Charlie Sheen, and Pierce Brosnan, who turned down the role because he couldn't take seriously the idea of playing a hero in tights.

13.Jack Nicholson played the Joker in that film, but he received top billing over Keaton's Caped Crusader. He also was smart enough to demand a percentage of the merchandising, resulting in a payday for the film that was worth between $60 and $90 million.

14. Bob Kane, the artist who (with writer Bill Finger) created Batman in 1939, was supposed to have a cameo 50 years later in Burton's film, but while he served as a consultant on that film (and the next three), he was too ill to appear in the film. But the fanciful sketch of the winged vigilante that reporter Knox (Robert Wuhl) is shown comes from Kane's pen and bears his signature.

15. Burton and Keaton reteamed for a successful sequel, 1992's "Batman Returns," but after that, Burton begged off the series, claiming he'd had a nervous breakdown making the second film, Keaton was game to return, but Warner Bros. deemed his demands unreasonable and replaced him with Val Kilmer for 1995's "Batman Forever."

16. Robin didn't appear in either of the Burton-Keaton movies, but the character appeared in early scripts for both movies. Kiefer Sutherland was considered for the first film, and Marlon Wayans was up for the part in the second.

17. After Joel Schumacher directed "Batman Forever," he broke Hollywood protocol and openly blasted Kilmer for being difficult on the set. "What's the worst that could happen to me?" Schumacher said of his undiplomatic candor. "That I'll never work with Val Kilmer again?"

18. Indeed, Schumacher's next Bat-film was "Batman and Robin," starring George Clooney as Bruce Wayne. The film was widely derided by Bat-fans for its campiness (that rubber-nippled Bat-suit!), killed off the film franchise for nearly a decade, and was named the worst film of all time by readers of Britain's Empire magazine. Schumacher said the studio pressured him to make the movie frothier than the previous installments. "Adults think kids are too scared of Batman, so we had to make it more kid-friendly, make it funnier, make it lighter," he said in a 2003 interview with The A.V. Club. Still, he accepted the blame for the final product. "I take full responsibility. It's all me. I know I disappointed some people, but it's a Batman movie. We're at war. Let's get over it."

19. Before Warners finally hired Christopher Nolan to direct what became the "Dark Knight" trilogy with Christian Bale, several other Batman movie projects died in development. Darren Aronofsky was to direct a "Batman: Year One" adaptation, based on the late-'80s DC title that covered Bruce Wayne's earliest days as a crimefighter. But he dropped out to make "The Fountain." And Wolfgang Petersen was going to do "Batman vs. Superman," but he dropped out to make "Troy." And then Warners decided to shelve the superhero duel in favor of a lighter Superman story -- which also went through several iterations before becoming the 2006 movie "Superman Returns," with Brandon Routh.

20. The Tim Drake character, one of the later Robins in the comics, was the apparent inspiration for John Blake, the character played by Joseph Gordon-Levitt in "The Dark Knight Rises."

21. In the comics, Batman has an online alias. It's JonDoe297.

22. He also has a favorite food: Mulligatawny soup.

23. The actor who has logged more time as Batman than anyone else is Batman: The Animated Series" in 1992. Over the past 23 years, he's been Batman in eight TV series, one animated feature film, two TV movies, 10 home video movies, and 10 video games.

24. Batman plays a central role in no fewer than seven current DC titles.

25. In recent years, the owners of the original Bat-copter from the Adam West series have been taking the half-century-old chopper around to state fairs and such, selling rides.