It was 75 years ago this week that criminals first stammered "Th...th...th...BAT-MAN!"
Thank you, Bob Kane...and Bill Finger, Jerry Robinson & Gardner Fox.
Above art by Bob Kane, scanned from recently-discovered page proofs of Detective Comics #27 (1939), is his first appearance in a story.
(He's also on the first page of the tale, but in silhouette.)
BTW, those first-generation proofs as close as any of us will ever get to the long-lost original art.