9/23/1935 The Saint takes over from Sam Spade, for spying, sort of

September 23, 1935.  Secret Agent X-9 was a comic strip, originally written by Dashiell Hammett and drawn by Alex Raymond (better known for Flash Gordon).  X-9 was the only spy in history who was addressed by his secret spy number instead of his name (huh?).  The agency he worked for was equally nameless.

X-9's adventures began in 1934 but on this date the authoring duties transferred from Hammett, the creator of Sam Spade, to Leslie Charteris, better known as the creator of the Saint. Seldom has so much talent been spent on so little a result.

Charteris left the strip a year later but it limped on with a  pseudonymous author (joining the agent and his agency in namelessness, I guess), until 1992.

10/4/1931 Dick Tracy arrives on the scene

October 4, 1931.  One of the longest running crime stories in history began on this day when Chester Gould's Plainclothes Tracy, later Dick Tracy, hit the funny pages.  Gould wrote and drew it for 46 years.  Among those who have contributed since are the noted novelist Max Allan Collins.

5/1/1939 Batman flies in

May 1, 1939.  The 27th issue of Detective Comics changed the comics world forever.  It featured "the world's greatest detective," the Batman (also known as the Dark Knight, the Caped Crusader, and that nut with the rodent obsession).  He has managed to stick around.