Capo de tutti capi

Its an italian phrase which literally translates to Boss of Bosses. Now when the mafia was constructed and organized by Charlie Lucky Luciano and Meyer Lanksy they formed the five families of new york and they made a commision or like a board of directors for all the organized crime familys where the boss of each family had a spot on the commision. Now on that commision there was a head of the board hence the name Boss of Bosses. He would have that spot because he had strongest and largest organzed crime family.