The Mafia was a criminal organisation.
When the Seventh Doctor was pretending to sell drugs to aliens in the 1990s, he achieved a position just below the head of the Chinese mafia. During that time, Lieutenant Morozich, a crewman on the Russian submarine Zhukov, contacted a representative of the Russian Mafia and sold him both a strange ore sample and the naval charts indicating where it was found. (PROSE: Bullet Time)
The Master acquired a casino in Las Vegas to accumulate the money needed to fund the experiments to elongate the lifespan of his host bodies, while also becoming head of the Hudson Dusters, and controlling part of the mafia. (AUDIO: Mastermind)