Very streetwise characters who are great with numbers and have a thin veneer of stylish respectability. The two examples I listed in the title are both fairly minor characters, but damn their lives'd probably make for some great reading.
West Indian Archie is a gangster figure in WW2 Harlem, from Spike Lee's Malcolm X biopic. The movie says Archie's involved in "a little of this, a little of that," but we mainly see him involved with the illegal lottery of the day, "the numbers." Archie has (near-)perfect recall of all the numbers involved in his racket, and presumably others as well, to the point that Malcolm X believes he could've been a great mathematician. A dapper dresser with a small entourage of suited-and-booted killers, he's a fixture of upscale restaurants and jazz clubs.
The other character I mentioned is le Chiffre, from the Bond novels. From what I understand, he's basically the finance guy for a trade union slash secret communist fifth column. From his description on Wikipedia:
Height 1,73 m. Weight 114,3 kg. Complexion very pale. Clean-shaven. Hair red-brown, 'en brosse.' […] False teeth of expensive quality. […] Dresses well and meticulously, generally in dark double-breasted suits. Smokes incessantly Caporals, using a denicotinizing holder. At frequent intervals inhales from benzedrine inhaler. Voice soft and even. Bilingual in French and English. Good German. Traces of Marseillais accent. Smiles infrequently. Does not laugh. Habits: Mostly expensive, but discreet. Large sexual appetites. Flagellant. Expert driver of fast cars. Adept with small arms and other forms of personal combat, including knives. Carries three Eversharp razor blades, in hatband, heel of left shoe, and cigarette case. Knowledge of accountancy and mathematics. Fine gambler.
Protagonists like these would be ideal, but as long as they're prominent in the story, I don't mind. Bonus points for authors that have credible experience! If you memoirs and autobiographies of people along these lines, those'd be also be much appreciated.
by justquestionsbud