His nickname of “Buddy” hovered in the murky middle between friendly engagement and what’s-it-to-you aggression. Either way, it seemed to capture Vincent A. Cianci Jr., the former mayor of Providence, R.I., known for his finger-snap wit, protracted troubles with the law, and unfailing devotion to his city.

Mr. Cianci died on Thursday morning after falling ill on Wednesday night while taping a weekly television show that featured his skills as a vexing, amusing polemicist. The buddy of Providence was 74.

Although Mr. Cianci had not been mayor since his federal conviction for racketeering in 2002, the shadow he cast over the city for 40 years is difficult to overstate. Even while serving his sentence in a federal penitentiary in New Jersey, the man seemed present. If you told a stranger you were from Providence — or even from Rhode Island — one question invariably followed: What’s Buddy like?

The answer was never pat. Short, compact and faintly menacing, Mr. Cianci walked about Providence with the swagger of a man who left his imprint on the skyline and even the pavement of the city. But his strutting could never quite shake the tragic air that enveloped him: a gregarious man who seemed lonely; a supremely gifted politician whose ego and foibles had brought him low; a walking coulda-been.