1939 Detective Comics Issue #27
Prior to getting his own imprint, Batman made his debut on March 30, 1939 in issue #27 of Detective Comics. "The Case of the Chemical Syndicate" takes up just six of the comic's 64 pages, yet establishes the characters of Batman, Bruce Wayne — revealed to be the Caped Crusader in the shocking final three panels — and Commissioner Gordon, as well as the gritty backdrop of Gotham City. This particular example is CGC graded 6.5 out of 10 with cream to off-white colored pages, and is one of just 36 complete examples in CGC's database, with only eight graded higher. It's up for sale now at Goldin Auctions and will remain open for bidding until May 21st.