Kalevi Sorsa
Sorsa was a leading political figure during the presidencies of Kekkonen and Koivisto. He was the chairman of the Social Democratic Party from 1975 to 1987 and was Prime Minister of Finland in four cabinets for a total of ten years (1972–1975, 1977–1979, 1982–1983, 1983–1987). He remains Finland's longest-serving prime minister.