Licio Gelli (Italian: [ˈliːtʃo ˈdʒɛlli]; 21 April 1919 – 15 December 2015) was an Italian Freemason, businessman, and terrorist. A fascist volunteer in his youth, he is chiefly known for his role in the Banco Ambrosiano scandal and in the Bologna massacre. He was revealed in 1981 as being the Venerable Master of the clandestine Masonic lodge Propaganda Due (P2). This would lead to him getting arrested in Switzerland in 1982. He managed to escape from prison the next year, but eventually agreed to surrender him back into the custody of Swiss authorities for a short period of time in 1987. From 1996 until his death in 2015, Gelli remained mostly under house arrest at his home in Arezzo, Italy.

Gelli was born in Pistoia, Tuscany. During the 1930s, Gelli, then a seventeen-year-old student at a liceo classico in Pistoia, was expelled from all schools in Italy after slapping a teacher. He subsequently left as a volunteer to fight in Spain with the Fascist brigades supporting Generalissimo Francisco Franco. It was in the battle of Malaga that his brother Raffaello died. The youngest recruit in his contingent, he was decorated by Franco himself.

Gelli also volunteered for the Blackshirts expeditionary forces sent by Mussolini in support of Francisco Franco's rebellion in the Spanish Civil War. He served as liaison officer between the Italian government and Nazi Germany, and participated in the Italian Social Republic with Giorgio Almirante, founder of the neofascist Italian Social Movement (MSI).

After a sales job with the Italian mattress factory Permaflex, Gelli founded his own textile and importing company.

In 1970, in the plans of the failed Golpe Borghese, Gelli was tasked with arresting the Italian President, Giuseppe Saragat. As Master of the Propaganda Due (P2) lodge, Gelli had ties with very high level personalities in Italy and abroad, in particular in Argentina, where he was a fugitive for many years. The regular Masonic lodge was enjoyed by Guillermo Suárez Mason and José López Rega, two key-exponents of the Argentine military junta.

The Argentine Chancellor Alberto Vignes drafted with Juan Perón, who had returned from exile in 1973, a decree granting Gelli the Gran Cruz de la Orden del Libertador in August 1974, as well as the honorary office of economic counselor in the embassy of Argentina in Italy. Gelli publicly declared on repeated occasions that he was a close friend of Perón, although no confirmation ever came from South America. Gelli affirmed that he introduced Peron to Masonry and that this friendship was of real importance for Italy. He stated: "Peron was a Mason, I initiated him in Madrid in Puerta de Hierro, in June 1973." Gelli become the main economic and financial consultant of Isabel Perón and of José López Rega.

According to a letter sent by Gelli to César de la Vega, a P2 member and Argentine ambassador to the UNESCO, Gelli commissioned P2 member Federico Carlos Barttfeld to be transferred from the consulate of Hamburg to the Argentine embassy in Rome. Gelli was also named minister plenipotentiary for cultural affairs in the Argentine embassy in Italy, thus providing him with diplomatic immunity. He had four diplomatic passports issued by Argentina, and has been charged in Argentina with falsification of official documents. During the 1970s, Gelli brokered three-way oil and arms deals between Libya, Italy and Argentina through the Agency for Economic Development, which he and Umberto Ortolani owned.

Several members of the Argentine military junta have been found to be P2 members, such as Raúl Alberto Lastiri, Argentina's interim president from 13 July 1973 until 12 October 1973, Emilio Massera, part of Jorge Videla's military junta from 1976 to 1978, and José López Rega, the infamous founder of the Argentine Anticommunist Alliance ("Triple A"). The lodge P2, also known as the Propaganda Due, was also linked to the robbery of Juan Perón's severed hands.