Today, March 30th marks the official 75th Anniversary of The Batman's First Appearance!!
National Periodicals Publications (today known as DC Comics) published the May issue (issue #27) of Detective Comics. This was the first issue that featured a brand new character called "The BAT-MAN", in a story called "Case of the Chemical Syndicate", written by Bill Finger and with artwork by Robert Kane.
This issue hit newsstands on March 30th, 1939!
The rest, as they say, is history...