Mehmet Ali Ağca (Turkish: [mehˈmet aˈli ˈaːdʒa]; born 9 January 1958) is a Turkish hitman for Grey Wolves. On 1 February 1979, he murdered journalist Abdi İpekçi, known for his leftist views, and was imprisoned, but escaped. He travelled illegally to Vatican City on 13 May 1981, and attempted to assassinate Pope John Paul II on the same day. However, the assassination attempt failed, and he was captured and imprisoned by the Italian police.

After being imprisoned for 19 years in Italy where he was visited by the Pope, he was deported to Turkey, where he served a ten-year sentence. Ağca was released from prison on 18 January 2010. He described himself as a mercenary with no political orientation, although he is known to have been a member of the fascist, Turkish ultra-nationalist Grey Wolves, as well as the state-sponsored Counter-Guerrilla.

In 2014, thirty-three years after his crime, Ağca visited Vatican City to lay white roses on the tomb of the recently canonized John Paul II, and said he wanted to meet Pope Francis, a request that was denied.

Mehmet Ali Ağca was born on 9 January 1958 in Hekimhan in a poor Turkish peasant family.

As a youth, he became a petty criminal and a member of numerous street gangs in his hometown. He became a smuggler between Turkey and Bulgaria. He claims to have received two months of training in weaponry and terrorist tactics in Syria as a member of the Marxist Popular Front for the Liberation of Palestine (PFLP) paid for by the Communist Bulgarian government, although the PFLP has denied this.

After training, Ağca went to work for the ultranationalist Turkish organization Grey Wolves. On 1 February 1979, in Istanbul, under orders from the Grey Wolves, he murdered Abdi İpekçi, editor of the major Turkish newspaper Milliyet. After being denounced by an informant, he was caught and sentenced to life in prison. After serving six months, he escaped with the help of Abdullah Çatlı, second-in-command of the Grey Wolves, and fled to Bulgaria, which was a base of operations for the Turkish mafia. According to investigative journalist Lucy Komisar, Ağca had worked on İpekçi's assassination with Çatlı, who then reportedly helped organize Ağca's escape from an Istanbul military prison. According to Komisar, some have suggested Çatlı was even involved in the Pope's assassination attempt. According to Reuters, Ağca had escaped with suspected help from sympathizers in the security services. Komisar added that at the scene of the Mercedes-Benz crash where Çatlı died, he was found with a passport under the name of "Mehmet Özbay" — an alias also used by Ağca.

In 1979 The New York Times reported that Ağca, whom it called "the self-confessed killer of an Istanbul newspaperman", had described the Pope as "the masked leader of the Crusades" and threatened to shoot him if he did not cancel his planned visit to Turkey, which went ahead in late November 1979. The paper also said (on 28 November 1979) that the killing would be in revenge for the then still ongoing attack on the Grand Mosque in Mecca, which had begun on 20 November, and which he blamed on the United States or Israel.

Beginning in August 1980, Ağca began criss-crossing the Mediterranean region. According to his later testimony, he met with three accomplices in Rome, one a fellow Turk and the other two Bulgarians. The operation was commanded by Zilo Vassilev, the Bulgarian military attaché in Italy. He said that he was assigned this mission by Turkish mafioso Bekir Çelenk in Bulgaria. Le Monde diplomatique, however, has alleged that the assassination attempt was organized by Abdullah Çatlı "in exchange for the sum of 3 million marks", paid by Bekir Çelenk to the Grey Wolves.