Informed minority

Generally, the "informed minority" in a Mafia game is the scum - even in a theme game where the "pro-town" players are criminals, the small but powerful group trying to achieve a win through night choices is strengthened by knowing who each other are. They then use this advantage against the uninformed majority to manipulate them into helping dwindle their numbers down to satisfy the smaller group's win condition (usually, equal or greater numbers than any other faction).

There may be multiple informed minorities (factions) in a single game, and together they may even total a majority of the players in a particular game, but each is working toward their own agenda.