Ilich Ramírez Sánchez (Spanish: [iˈlitʃ raˈmiɾes ˈsantʃes]; born 12 October 1949), also known as Carlos the Jackal (Spanish: Carlos el Chacal) or simply Carlos, is a Venezuelan convict who conducted a series of assassinations and terrorist bombings from 1973 to 1985. A committed Marxist–Leninist, he was one of the most notorious political terrorists of his era, protected and supported by the Stasi and the KGB. After several bungled bombings, Carlos led the 1975 raid on the Organization of the Petroleum Exporting Countries (OPEC) headquarters in Vienna, during which three people were killed. He and five others demanded a plane and flew with a number of hostages to Libya.

After his wife Magdalena Kopp was arrested and imprisoned, Carlos detonated a series of bombs, claiming 11 lives and injuring more than 100, demanding the French release his wife. For many years he was among the most-wanted international fugitives. He was ultimately captured by extrajudicial means in Sudan and transferred to France, where he was convicted of multiple crimes, and is currently serving three life sentences. In his first trial, he was convicted of the 1975 murder of an informant for the French government and two French counterintelligence agents. While in prison, he was further convicted of attacks in France that killed 11 and injured 150 people and sentenced to an additional life term in 2011, and then to a third life term in 2017.

Ramírez Sánchez, son of Marxist lawyer José Altagracia Ramírez Navas and Elba María Sánchez, was born in Michelena, in the Venezuelan state of Táchira. Despite his mother's pleas to give their firstborn child a Christian first name, José called him Ilich, after Vladimir Ilyich Lenin, while two younger siblings were named "Lenin" (born 1951) and "Vladimir" (born 1958). Ilich attended high school at Liceo Fermin Toro [es] in Caracas and joined the youth movement of the Venezuelan Communist Party in 1959. After attending the Third Tricontinental Conference in January 1966 with his father, Ilich reportedly spent the summer at Camp Matanzas, a guerrilla warfare school run by the Cuban DGI near Havana. Later that year, his parents divorced.

His mother took the children to London, where she studied at Stafford House College in Kensington and the London School of Economics. In 1968, José tried to enroll Ilich and his brother at the Sorbonne in Paris, but eventually opted for the Patrice Lumumba University in Moscow. According to the BBC, it was "a notorious hotbed for recruiting foreign communists to the Soviet Union" (see active measures). He was expelled from the university in 1970.

From Moscow, Ramírez Sánchez travelled to Beirut, Lebanon, where he volunteered for the Popular Front for the Liberation of Palestine (PFLP) in July 1970. He was sent to a training camp for foreign volunteers of the PFLP on the outskirts of Amman, Jordan. On graduating, he studied at a finishing school, code-named H4 and staffed by Iraqi military, near the Syria-Iraq border.

When Sánchez joined the Popular Front for the Liberation of Palestine (PFLP) in 1970, recruiting officer Bassam Abu Sharif gave him the code name "Carlos" because of his South American roots. Sánchez was dubbed "The Jackal" by The Guardian after one of its correspondents reportedly spotted Frederick Forsyth's 1971 novel The Day of the Jackal on the bookshelf of a friend's apartment in which Sánchez had stashed some weapons. The book belonged to a resident in the apartment, not Sánchez, who probably never read it.

On completing guerrilla training, Sánchez (who had begun going by his surname) played an active role for the Popular Front for the Liberation of Palestine (PFLP) in the north of Jordan during the Black September conflict of 1970, gaining a reputation as a fighter. After the organisation was pushed out of Jordan, he returned to Beirut. He was sent to be trained by Wadie Haddad. He eventually left the Middle East to attend courses at the Polytechnic of Central London (now known as the University of Westminster), and apparently continued to work for the PFLP.

In 1973, Sánchez conducted a failed PFLP assassination attempt on Joseph Sieff, a Jewish businessman and vice president of the British Zionist Federation. On 30 December, Sánchez called on Sieff's home on Queen's Grove in St John's Wood and ordered the maid to take him to Sieff. Finding Sieff in the bathroom, in his bath, Sánchez fired one bullet at Sieff from his Tokarev 7.62mm pistol, which bounced off Sieff just between his nose and upper lip and knocked him unconscious; the gun then jammed and Sánchez fled. The attack was announced as retaliation for Mossad's assassination in Paris of Mohamed Boudia, a PFLP leader.