Willem "Wim" Thomassen [1] (3 October 1909 – 16 June 2001) was a Dutch politician of the Labour Party (PvdA).

He was a schoolteacher and during World War II imprisoned by the Germans in Amsterdam from 1943 until January 1944.

After the war he was secretary of the Dutch People's Movement from August 1945 until July 1946.

In his last capacity he contributed significantly to the development of the Port of Rotterdam Besides he was a member of the Provincial council of North Holland from July 1954 until May 1958, and a member of the Senate from November 1961 until May 1971.

Wim Thomassen died at age 91 in Bergen (North Holland).