Marianne Leonie Petrus Thyssen (Dutch pronunciation: [maːriˈjɑnə ˈtɛisə(n)]; born 24 July 1956) is a Belgian politician of the Christian Democratic and Flemish Party (CD&V) who served as European Commissioner for Employment, Social Affairs, Skills and Labour Mobility between 2014 and 2019.

She worked as a legal adviser for a Belgian organisation for the self-employed and small and medium-sized businesses UNIZO and the women's network Christelijke Middenstands- en Burgervrouwen (CMBV) now Markant, becoming Director then acting Secretary-General at UNIZO in 1991.

From 1986-1988 she acted as legal adviser to the state secretary for public health and disability policy.

In 1991, Thyssen became a Member of the European Parliament (MEP) for Flanders with the CD&V, the Flemish Christian Democrats in Belgium; she took the place of Karel Pinxten [nl], who had moved to the Belgian Senate.

As a local councillor, she chose to work on such social issues as childcare and care for the elderly.