Marc Maria Frans, Viscount Eyskens (born 29 April 1933), known as Mark Eyskens, is a Belgian economist, professor and politician in the Christian People's Party, now called Christian Democratic and Flemish, and briefly served as the prime minister of Belgium in 1981.

When Germany invaded Belgium, Eyskens and his mother fled to France but upon the Belgian capitulation, the family returned to Leuven.

In 1962, Eyskens started his political career as a counsellor in the cabinet of the Minister of Finance André Dequae.

Eyskens became the 45th Prime Minister of Belgium on 6 April 1981, an office his father had held six times.

His government quickly collapsed on 17 December, due to disagreements on the financing of the Walloon steel industry.