I’m curious to know many Black Mask characters graduated into original novels after (or during) their time with the magazine. I can name only two from the Shaw years, and W.T. Ballard’s Bill Lennox is one of them. The other is George Harmon Coxe’s Flash Casey
Race Williams doesn’t really count because—like Sam Spade and the Continental Op—his novel-length adventures had appeared first in the magazine (along with one - I think - in Dime Detective).
Moving beyond the Shaw years, Robert Reeves' Cellini Smith would qualify, and there were likely others.
But Bill Lennox is probably unique in that he not only graduated, but took his Black Mask style along with him. The four Lennox novels are Say Yes to Murder (1942) (reviewed HERE), Murder Can’t Stop (1946), Dealing Out Death (1948) and Lights, Camera, Murder (1960).
Lennox is described as a troubleshooter for Sol Spurck, head of Hollywood’s General-Consolidated Studios. In between making Spurck’s troubles go away, he’s apparently free to do what he wants, and what he enjoys most is discovering would-be starlets and nurturing their careers. Though it’s never really stated, this hobby is one of the main factors in his long term job security. The more starlets he takes under his wing, the more trouble they get into, and the more trouble there is for him to shoot.
That’s the driving force behind Dealing Out Death. Bill’s starlet of the moment has a no-good brother in trouble in Las Vegas and shirks her studio responsibilities to help him. Lennox has no choice but to follow her to Vegas, where—as you would expect—much more trouble ensues.
This novel presents an interesting pre-mob look at Sin City. The city fathers and casino operators are fighting to keep the mobsters from gaining a foothold, and Lennox—protecting the interests of his starlet and studio—becomes their unwilling ally. This novel takes place ten or more years before the events in the lamented 2013 TV series Vegas, when we saw that foothold gained.
Stylistically, Ballard was no Hammett, but he knew how to tell a good tale and keep it hopping, and Dealing Out Death is a fine example. It’s also a FREE example, because you can download it in a variety of electronic formats from Munseys.com. You’ll find it HERE.