Before there was Batman, there was the Bat. Bob Kane was obviously a fan of the silent movie made in 1926 by Roland West which was based on the 1920 hit Broadway play by Mary Roberts Rinehart and Avery Hopwood.
The movie has to do with a group of people all spending the night in a creepy house, looking for a lost fortune in a secret room. Unbeknown to them, they are joined by The Bat, a creepy thief that murders people in the group one by one. The Bat is pretty interesting, he dresses up like a giant bat. Not like the Batman, just actually in a giant bat costume. It’s pretty strange. However, according to Bob Kane this character was the inspiration for Batman. Hell, they even had a Bat Signal in the movie. (source)