The Batman Serial

Behold Batman in his low-budget glory

In 1943, Columbia Pictures released a serial based on Batman. For the unaware, serials were (often low budget) short action films that were part of a mutlipart story. Said serials would be shown prior to a movie. In this version of Batman, Batman and Robin worked for the FBI and none of Batman's villains from the comic appear due to regulations at the time.
Plot
FBI agents Batman (Lewis Wilson) and Robin (Douglas Croft) fight against the Japanese mad scientist Doctor Tito Daka (J. Carrol Naish), who is working for Hirohito. Daka's base is a fun house in Gotham's Japanese district. Daka attempts to stop the Duo several times, but always fail. He ends up falling into a pit full of crocodiles.
Influence On the Batman Mythos 
Despite the fact you propably never heard of this before, it was extremely important to the Batman mythos. The Batcave (called "the Bat's Cave" in the serial) and its grandfather clock enterance were introduced here. Originally, Alfred was both overweight and mustacheless. However, this serial introduced the now-popular look of the character.
Alternate Versions and Releases
Several alternate version of the serial exist. In 1965, the serial was collected and reaired as "An Evening With Batman and Robin". The program was just the episodes complete with titles, cliffhangers and credits. Goodtimes' release of the serial edited out the racist dialogue (which was due to it being made during World War II). However, a "restored" version retained the dialogue. In the late 1960s, the shortened versions of the individual episodes were released to the home market on the 8mm format.
References:
http://en.wikipedia.org/wiki/Batman_(serial)
http://www.imdb.com/title/tt0035665/
http://www.imdb.com/title/tt0035665/trivia?ref_=tt_trv_trv
http://www.imdb.com/title/tt0035665/alternateversions?ref_=tt_sa_4