Bob Kane created Batman. That's the official history, and he gets all the credit. The reality, as always, is more complicated, and it turns out that a huge amount of what we know as Batman - possibly just about everything we know about Batman, including Bruce Wayne, Commissioner Gordon, The Batcave, Robin, the look of the costume and... well, everything except the name of the character - came from a guy named Bill Finger. Finger's never gotten his due (partially, I've read, because of a disposition that didn't lend itself to fighting for credits) but as his 100th birthday approaches (February 8th) some creators are hoping to give everybody The Finger - the Bill Finger - by celebrating his contributions, possibly with a Google Doodle. Visit Templeton's site for details on how to bug Google about it.
Ty Templeton created this comic, illustrating what a Batman adventure might have been like if Bob Kane was the sole creator, as has been often stated: