Oskar Fischer (born 19 March 1923 in Aš, Czechoslovakia) was an East German politician who served as minister of foreign affairs of the German Democratic Republic from 1975 to 1990.
Fischer served as East Germany's ambassador to Bulgaria for four years. He was deputy minister of foreign affairs from 1965 to 1975. He was named as a member of the Central Committee of the Socialist Unity Party in 1971. He was appointed as minister of foreign affairs on 3 March 1975. Fischer replaced Otto Winzer in the post, who had been removed from office due to ill health.
Oscar Fischer was the first member of the East German cabinet to visit Pope John Paul II at the Vatican in 1978. Fischer also officially visited a number of European states, including Austria, Denmark and the Netherlands. Fischer's tenure lasted until 12 April 1990.
At the beginning of the 2000s, Fischer served as one of the advisors to Gabriele Zimmer.