Petras Griskevicius (July 19th, 1924 in Kriaunos, Rokiskis district – November 14th, 1987 in Vilnius) was a high-level communist party official in the Lithuanian SSR. He was the First Secretary of the Lithuanian Communist Party (de facto leader of Lithuania) from 1974 to his death.

At the beginning of World War II, Griskevicius retreated into the Russian SFSR. During the war, he was a member of the 16th Rifle Division (1942 – 1943) and a Soviet partisan (1943 – 1944) in Rokiskis district. After joining the communist party in 1945, he slowly rose through the ranks. He worked in press censorship (1950 – 1955) before moving to the Vilnius committee of the Lithuanian Communist Party. There he worked at the secretariat (1955 – 1964) and central committee (1964 – 1971), becoming the first secretary in 1971.] After the death of Antanas Snieckus in 1974, Griskevicius succeeded him as the First Secretary of the Lithuanian Communist Party. He was also a delegate of the Supreme Soviet of the Lithuanian SSR (since 1965), delegate of the Supreme Soviet of the Soviet Union (since 1974), and member of the Central Committee of the Communist Party of the Soviet Union (since 1976). Griskevicius was described as a Brezhnevite, conservative and "mediocre apparatchik", who opposed perestroika and especially glasnost. He supported suppression of Lithuanian history and cultural heritage, replacing them with Soviet propaganda.