Big fan of the important cogs who never made a ton of noise:

Ross Prio(CHI), Carmine Lomardozzi(NY), each had more money than most wise guys could earn in 5 lifetimes

Pat Marcy's real name was Pasquale Marchone. He changed it and reigned over the 1st Ward of Chicago for over 3 decades, and when they finally found someone in his inner circle to flip...he died during trial an old man.

I could go with the obvious and rattle off a bunch of the most notorious guys there were, but I'd rather post a few slightly obscure names and see who else were fans of the quite guys as well

also the guys who ran the zip crews, people like Patsy Conte who built up their power by aligning with the italian mobs in sicily and bringing guys over. Not to mention their confusing success in the heroine trade, a business that 90% of their counterparts to this day can't very successfully figure out who longs periods of time