Mario Tanassi (17 March 1916 – 5 May 2007) was an Italian politician, who was several times Minister of the Italian Republic. In 1979 he was condemned by the Constitutional Court of Italy for his involvement in the Lockheed bribery scandal.
Tanassi was born at Ururi, in the province of Campobasso. He entered the Italian Democratic Socialist Party (Partito Socialista Democratico Italiano, or PSDI) and was alter national co-secretary, together with Francesco De Martino, of the unified PSI-PSDI, a short-lived reunion of PSDI and the Italian Socialist Party.
He was minister of defence for the first time in the Rumor II Cabinet (1970), formed by an alliance between Christian Democracy (DC), PSI and PSDI. In 1972 he was again appointed as minister of defence, as well as vice-prime minister (Andreotti II Cabinet, in which the Italian Liberal Party had replaced the Socialists). Tanassi was minister of defence for the third time in the fourth Rumor Government (DC-PSI-PSDI-PRI).
After a short tenure in 1972, in June 1975 he became again national secretary of PSDI, replacing Flavio Orlandi. A few time later, he was involved in the Lockheed bribery scandal together with Mariano Rumor and Luigi Gui, and therefore he lost the position of the party's secretary. In 1979 the Constitutional Court of Italy found him guilty of bribery and he spent fourth months in jail. He was the first Italian former minister to undergo a prison condemn and first politician convicted before the nationwide Clean Hands anticorruption movement.