Mehdi Ben Barka (1920 in Rabat – 1965? in Paris) was a Moroccan politician. Ben Barka was born to a civil servant and became the first Moroccan to get a degree in mathematics in 1950. He became a prominent member of the Moroccan opposition (his party was the nationalist Istiqlal) and reportedly supported Algeria over Morocco during the 1963 Moroccan invasion of that country, which led to decades of tense relations between the two states. Ben Barka was a major figure in the Third World movement and supported revolutionary action in various states. During the 1960s, the governments of Morocco, the United States, and France enacted savage repression of dissidents and Ben Barka was no exception. On 29 October 1965, Ben Barka, an outspoken opponent of Moroccan King Hassan II, was “disappeared” by French police officers and never seen again.

A 1967 trial saw two French officers go to prison for their role in the kidnapping, However, the judge ruled that the main guilty party was Moroccan interior minister Mohamed Oufkir . Georges Figon , a witness with a criminal background, who had testified earlier that Oufkir stabbed Ben Barka to death, was found dead, officially a suicide.

A former member of the Moroccan secret service, Ahmed Boukhari revealed in 2001 that Ben Barka had died during interrogation in a villa south of Paris. He said Ben Barka's body was then taken back to Morocco and destroyed in a vat of acid.

In 1976, the United States government, due to requests made through the Freedom of Information Act, acknowledged that the Central Intelligence Agency was in possession of some 1,800 documents involving Ben Barka, but the documents were not released. Some secret French documents on the affair were made public in 2001, causing political uproar. Defence minister Michèle Alliot-Marie had agreed in 2004 to follow the recommendations of a national defence committee and release the 73 additional classifed documents on the case.