Gaston François Marie, Viscount Eyskens (1 April 1905 - 3 January 1988) was a Belgian economist, Christian Democratic politician of the CVP - PSC, and statesman.

He was a six-time Prime Minister of Belgium from 1949 to 1950, 1958 to 1961 and 1968 to 1973. Eyskens was confronted with major ideological and linguistic conflicts (the controversy over king Leopold III in 1950, the "School War" in 1958, the split of the University of Leuven in 1970). He oversaw the first steps towards the regionalization of Belgium (constitutional reform of 1970).

Eyskens was born in Lier, the son of Antonius Franciscus Eyskens (1875 – 1948) and Maria Voeten (1872 – 1960), he married in 1931 Gilberte Depetter (1902 – 1981), with whom he had two sons Erik Eyskens (Leuven 20 July 1935 - Antwerpen 31 August 2008) and Mark Eyskens. His son Mark was Prime Minister from 6 April 1981 to 17 December 1981.

Gaston Eyskens studied at the University of Leuven where he gained a master and doctorate degree. In 1927 he became Master of Science at Columbia University. In 1931 Eyskens became a professor at the University of Leuven. He later became dean of the economics faculty. He also served on the board of the University of Lovanium. Eyskens was made doctor honoris causa by Columbia University, the University of Cologne and the Hebrew University of Jerusalem.

During the early 1930s Eyskens was chief of staff of CVP ministers Edmond Rubbens and Philip Van Isacker. In 1939 Eyskens became a member of the Belgian Chamber of Representatives. He was steadily reelected (1946, 1949, 1950, 1954, 1958 and 1961) and served until 1965.

In 1945 and between 1947 and 1949 he was Minister of Finance. On 11 August 1949 he became Prime Minister of Belgium in a coalition (Eyskens I) between Christian democrats and liberals. His cabinet fell in June 1950 over the constitutional crisis caused by King Leopold III’s actions during the Second World War. In the short lived government of Jean Duvieusart (June - August 1950) Eyskens was Minister of Economical Affairs.

Between 26 June 1958 and 6 November 1958, Eyskens lead a minority government which was the last government of Belgium (Eyskens II) which was not a coalition government. On November 6, Eyskens formed a coalition government with the liberals (Eyskens III) which remained in power until 3 September 1960. On 3 September 1960 he formed his third government (Eyskens IV), again a coalition with the liberal party. This government fell on 25 April 1961 over the Unitary Law (which raised the fiscal pressure with 7 billion Belgian francs, cut spending in education and the military, reformed the unemployment dole and government pensions) and had caused massive strikes. During these years he also had to handle the School War and the independence of the Belgian Congo.

In the general election of 1965 Eyskens was elected to the Belgian Senate (reelected in 1968 and 1971). In the government led by Pierre Harmel (1965 – 1966) he again served as Minister of Finance. Student unrest and questions of discrimination against ethnic Flemish brought down the Belgian government in February 1968. On 17 June 1968 Gaston Eyskens formed his fifth government (Eyskens V). This time a coalition between the Christian democrats and the socialists. On 20 January 1973 he formed his sixth and last government (Eyskens VI) again a coalition with the socialists.

His last two governments were plagued with linguistic troubles regarding the split of the old bilingual Catholic University of Leuven in a Dutch language university (the Katholieke Universiteit Leuven), which stayed in Leuven and a French language university which moved to Louvain-la-Neuve and became the Université catholique de Louvain and the start of the process of changing Belgium from a unitary state into a federation with the creation of the Communities. Upon the fall of his last government Gaston Eyskens retired from politics. He died in Leuven.

On 5 April 1963 Gaston Eyskens was made a Minister of State. On September 1973, Eyskens was ennobled as an hereditary viscount in the Belgian nobility.