Arnold Rothstein / Abe Redstone

Arnold Rothstein is New York's premier gambler and fixer, a soft-spoken financier of vice who treats crime as a discipline of ledgers, patience, and precision. He arrives in Atlantic City circles as a quiet outside power, testing Nucky Thompson's operation, always calculating, never raising his voice, always three moves ahead.

Michael Stuhlbarg plays him as a man allergic to disorder, fussy about napkins and exact change, which makes his ruthlessness land harder for being so unhurried. The writing lets him out-think louder men simply by waiting, and Stuhlbarg's stillness turns arithmetic into menace.