However, as I've stated before, what has made this particular hero the most popular among the pulp heroes listed above is not so much the flying rodent paraphanalia, or even the comic medium, but rather his villian/rogues gallery. For example, the most famous Sherlock Holmes villain is Dr. Moriarty, but most would have trouble identifying another. I'd be surprised if anyone could name a Doc Savage villain (John Sunlight), or Zorro, or The Shadow (he knows, though, he knows). I've decided to write a few posts about a few of my favorite villains, and about why they are so intriguing, and which versions of said villain I like the best.
The Joker is a good place to start.
Created by Bob Kane, Jerry Robinson and possibly Bill Finger too, the Joker made his debut in Batman #1 in 1940. This same issue also debuted Catwoman. The original premise of the character was a highly intelligent, yet psychotic master criminal (not unlike Professor Moriarty) with a warped, dark sense of humor. The character has, over time, flip-flopped from this original premise to a lighter, campier, prankster, and back again, depending on the era, and the medium. Some writers seem to have a difficulty portraying the character as dangerously intelligent, and also obsessed with punchlines. Often, I find myself frustrated with how the Joker character is written. He has come, recently, full circle with the help of Christopher Nolan and Heath Ledger, not only readopting and solidifying the intelligent psychotic persona, but adding an element of Chaos personified.
There have been attempts in the past, and I'm sure in the future as well, to try and fit the character into some sort of profile. There have been several attempts to give the character an origin, which I don't believe is necessary, and takes away from the twisted, chaotic nature of the character. Chaos has no origin story. A Joker origin gives him a timeline, and a timeline is order, which is not chaos.
There have been other things writers have attempted to add to the Joker's character and storyline that I try and dismiss as silly. For example, there is no reason for creating children for this character. Duela Dent was a stupid idea. Also, having him team up with other villains never made sense to me either, he doesn't seem to be the type of character to take orders, or play a role. Harley Quinn is really the only exception, but she's an interesting character for other reasons.
There have been a few cool additions to the character that I found interesting and should be explored more. In the Dark Knight film, Heath Ledger's character tells the story of how he "got these scars" differently each time, much like in the Killing Joke by Alan Moore when the Joker states that sometimes he remembers his origin one way and sometimes another.
There has also been an idea poised by writer Grant Morrison, that the Joker is not insane at all, but lacked a personality all his own. He has to continuously adapt his psyche, which explains why it appears that the Joker transitions often from dangerous super criminal, to campy joking prankster so many times in his published career. It seems like just a gimmick to make continuity make sense. Sometimes obsession with continuity leads comic writers to make bad decisions. There is another theory that the Joker is actually super sane, and works on a separate level than everyone else. The Dark Knight brings this idea up at the end of the film, when Batman tells the Joker "there's nothing wrong with you".
After considering all of this, the Joker is definitely worthy of being the most recognizable, most important foil for the Batman. And given how the portrayal of the character has been trending from Caesar Romero Joker, and Mark Hamil's animated series Joker back to the 1939 homicidal maniac Joker blended with the Heath Ledger lone agent of Chaos character, things are looking good for this Batman villian.