This must be the only photograph of most of the great hard-boiled crime writers who wrote for Black Mask magazine in the 1930s. In the back row, from left to right, are Raymond J. Moffatt, Raymond Chandler, Herbert Stinson, Dwight Babcock, Eric Taylor and Dashiell Hammett. In the front row, are Arthur Barnes, John K. Butler, W. T. Ballard, Horace McCoy and Norbert Davis.
William F. Nolan wrote novels featuring them as the Black Mask Boys.
The original photograph is online here.
Here's the website of Black Mask Magazine.