On the 30th March 1939, Batman made his first appearance when Detective Comics #27 went on sale. This particular comic is now widely considered to be one of the most valuable comics in the world, with the most expensive copy selling for $1,075,000 in February 2010. It originally retailed for 10 cents.
The first issue of Detective Comics appeared years earlier, in March 1937, and featured an anthology of hard-boiled detective stories. It was the third series to be released by National Allied Publications, which had experienced enormous success with Superman, and by early 1939 was looking to include more superheroes in its publications.
Batman was created by Bob Kane and Bill Finger, and first appeared in a story called “The Case of the Chemical Syndicate” along with Commissioner Gordon. In the story, the Bat-Man (with a hyphenated name) solves the death of a chemical manufacturer. At the end he is revealed to readers to be the alter-ego of billionaire philanthropist Bruce Wayne. The popularity of the character in subsequent issues of Detective Comics led to him being given his own title in 1940, which by 1941 was selling 800,000 copies every issue.
Interestingly, although the cover date of the first issue was May 1939, it was normal – as indeed it still is – for magazines to go on sale before their cover date. One reason is that an advance sale fools customers into thinking that a particular issue is still ‘current’ and so secure higher sales. Another reason is that cover dates act as an indicator to retailers of when to remove that issue from sale.