Aniello Dellacroce (March 15,1914 - December 2, 1985) was a gangster, and high-ranking member of the Gambino crime family, one of the five major Mafia factions in New York City.

Not a great deal is known about his early life, except that he rose in power within the Gambino Family after it was formed in 1957 following the death of Albert Anastasia. Carlo Gambino is thought to have ordered the murder of Anastasia, after which he took over Anastasia's crews and effectively formed the Gambino Family. Shortly after Gambino's crowning as Boss, he named Dellacroce his Underboss (second in command).

Like most 'old style' Mafiosi, Dellacroce did not attract attention to himself, and sometimes he even walked around Manhattan dressed as a priest and calling himself 'Father O'Neil', to confuse both the police and rival mobsters.

In 1976, Carlo Gambino died of natural causes, having declared his wish that Paul Castellano should be the new boss. Dellacroce had been tipped as the successor and was reportedly annoyed at the late Carlo's decision. A potential inter-family war was prevented, however, because just before Gambino died, he and Castellano agreed to have Dellacroce remain Underboss and furthermore, whilst Castellano concentrated on white-collar crimes like union racketeering and fraud, Dellacroce would have free reign over those crews who carried out more traditional, 'hands on' Mafia activities, such as robbery, hijacking and extortion. Castellano banned drug dealing in his family, but few took any notice of this, including the ambitious John Gotti, who was close to Dellacroce.

By 1985, Gotti was eager to kill Castellano so he, Gotti, could take over the Gambino Family. However, although Dellacroce was reported to despise Castellano, he was nonetheless committed to the Mafia code, which said that you could not murder your boss, and he demanded Gotti not take such a lethal course of action.

However, Dellacroce was suffering from cancer that year, and he died on December 2, aged 71. The way was now clear for Gotti to arrange for Castellano's assassination, which took place less than a fortnight later.