Back in 2006, when I looked in the article on Batman for some info on the origin of the character, I was surprised to discover no such section, so I wrote the below material for the article, somewhat hastily. It was later 'edited mercilessly', becoming the current "Creation" section, but I'm proud to have gotten the ball rolling on the subject. It's my opinion that articles on fictional subjects like this tend to acquire vast amounts of "in-world" cruft and very little of the "real world" information which is more appropriate content for an encyclopedia.
Character Origins edit
Created in the time before the modern concept of the superhero, Batman took after characters such as The Shadow, Zorro, and other noir-style crimefighters (The Spirit, The Spider, etc.).
The Shadow, who debuted earlier in the 1930s in radio and pulp fiction, had at least two major similarities to Batman: his "wealthy playboy" alter ego, and his penchant for operating under cover of darkness and using fear to disarm his criminal targets. Despite being a "good guy", he was made in the vein of the noir anti-hero, and thus would not hesitate to gun down his enemies.
Zorro, who first appeared in pulp fiction in 1919, likewise has inherited wealth from his parents, and poses as a harmless gentleman of high society. Like Batman, he operates from a hidden cave near his home, and is known for fighting for justice for the common man. Great emphasis is placed on his acrobatics and education, two attributes which Batman also possesses.
One could argue that certain of these traits were almost unavoidable in the crimefighters of the time. However, Batman's creators have routinely acknowledged these two characters as influences. Various retellings of the night Bruce Wayne's parents are murdered have depicted them as having just seen a "Zorro" movie, and, as far as The Shadow is concerned, Batman's creators specifically took care to distinguish their hero from the well-known crimefighter, taking away his gun early in his comic book adventures, and eventually giving Batman an anti-gun stance.
One can even trace Batman's roots further, though to lesser degrees of similarity, by looking at the influences for Batman's influences: Zorro was likely inspired by such characters as The Count of Monte Cristo and the Scarlet Pimpernel, wealthy swashbucklers both, one motivated by revenge, the other possessing an alter ego, and real-life personas such as Joaquin Murrieta, a Mexican bandit sometimes compared to Robin Hood and William Lamport, an Irishman who fought for Mexican independence in the 17th century.
Although those influences seem to bear little resemblance to the "Caped Crusader", Batman, they all possess an aspect of vigilantism. Well before characters such as Superman were introduced, who boldly fought crime in broad daylight with their superpowers, the heroes of literature that youth admired were mortal and depended on cunning and wit to survive. Aside from occasional "reboots" by comic book writers, most of the above characters are "obsolete", such as The Shadow. This makes "Batman" one of the last actively-published stories of an old-fashioned vigilante hero.