Pietro Aglieri (born June 6, 1959 in Palermo) is a Sicilian mafioso from the Guadagna neighbourhood in Palermo. He is known as U Signurinu ("The Little Gentleman") for his relatively sophisticated education and refined manners. He had a classical education and studied Greek, Latin, philosophy, history and literature to a level that guaranteed him entry to university. Instead he chose for a career in Cosa Nostra. The British journal The Guardian listed him as the emerging man of the year 1995 in Italy.
Aglieri was a loyal supporter of the Corleonesi clan of Totò Riina and Bernardo Provenzano during the Second Mafia War. He gained Riina's favour by killing relatives of a rival Mafia bosses. He became the boss of the Santa Maria di Gesù Mafia family after Giovanni Bontade – the brother of Stefano Bontade – was killed in 1988. Although active since the early 1980s, his name was not brought to prosecutors' attention until 1989.
As member of the Sicilian Mafia Commission, Aglieri was being tried in absentia for the 1992 bombing deaths of Italy's two top Mafia investigators, Giovanni Falcone and Paolo Borsellino, for which he received life sentences. He also received a life sentence for the murder on judge Antonino Scopelliti on August 9, 1991, who was killed while preparing the final sentence for the Maxi Trial for the Court of Cassation. He was also on trial for the 1992 murder of Salvo Lima, a Sicilian politician with close links to Giulio Andreotti, the former premier accused of Mafia association.
After the arrest of Riina in January 1993, Aglieri started to support Provenzano’s new less violent mafia strategy. The new guidelines were patience, compartmentalisation, coexistence with state institutions, and systematic infiltration of public finance. The diplomatic Provenzano tried to stem the flow of pentiti by not targeting their families, only using violence in case of absolute necessity.