Batman, as well as having that frightening other-worldly mysteriousness about him as already mentioned, is also deeply influenced by Gothicism. Which is probably one of the reasons he is my favourite superhero; who doesn't like a bit of Gothic symbolism in their fictional crimefighter? I happen to like bats too (excepting the time one nearly flew into my face while I was walking down a dark Devon lane) and what is Batman other than a man dressed as a bat? And bats are a Halloween staple!
The history of those 75 years is fascinating as well, with the character's origins from the 1930s and '40s (and earlier) just adding more to his appeal.
The Shadow and The Phantom. Going even further back, Zorro has been cited as an influence, something writers worked into Batman's origin story (it was the 1920 Douglas Fairbanks Sr. The Mark Of Zorro that the Wayne family saw before the parents were murdered outside the theatre). Bob Kane also took themes from popular culture of his youth - films like 1926's The Bat (and the 1930 remake/sequel The Bat Whispers) and Conrad Veidt's Gwynplaine in 1928's The Man Who Laughs. (As a result of this there are some excellent vintage Batman parodies to be found on YouTube...)
The Batman's next 75 years would seem to be assured, then, although rumblings continue over the decision to cast Ben Affleck in the role for the upcoming 2015 extravaganza that will be Batman vs. Superman. However that turns out I'm sure the Batman will endure, continuing his adventures and forever striking a fearful and unnatural shadow over the cowardly and superstitious criminal.
*Below are the two "vintage Batman" videos mentioned earlier. Who was your favourite Batman/Bruce Wayne? Is Ben Affleck a good choice to play the next Caped Crusader? Do let me know in the Comments section - and have a happy Halloween!