The Bosses are a ghostly syndicate made up of Meyer Lansky, Lucky Luciano, Bugsy Siegel, and Al Capone.
Since old habits die hard, the ghosts of the mob bosses Meyer Lansky, Lucky Luciano, Bugsy Siegel, and Al Capone formed a syndicate in the afterlife. In exchange for a "secret pipeline" in Purgatory that led to the real world, the Bosses would supply the demons with innocent souls off the record. However, the Ghostbusters unknowingly busted up a meeting relevant to their operations. Fred, their top lieutenant, reported back and asked for permission to seek retribution. While Siegel and Lansky were against putting out a hit on the living and risk exposing their operations, Luciano overruled them and ordered Fred to get rid of the Ghostbusters.
In Purgatory, the Ghostbusters were still a threat to the status quo so the Bosses made a deal with several souls to consign the guys to an eternity of oblivion in exchange for the right to cross over. This "Apple Dumpling Gang" failed to stop them so the Bosses forced Fred to un-retire and gather the Ghostbusters' equipment. The Bosses made a deal with a powerful demon to bring the Peter's Fred-possessed body to Purgatory. In exchange, the demon could have Peter. However, the Ghostbusters won again. Capone was taken into custody by J. Edgar Hoover, Jelly Bryce, and Elliot Ness for border violation charges.
A week after the Ghostbusters escaped Purgatory, they tracked down the remaining three ghosts to the church they convene in alongside a replacement, John Gotti. Never admitting defeat, the Bosses declared someone else would take over the Pipeline after them and nothing would change. The Ghostbusters then trapped them.
The Bosses are basic ghosts but due to their personalities in life, they have a knack for organized crime and brokering deals in the afterlife.