Willem Drees Sr. (5 July 1886 – 14 May 1988) was a Dutch politician of the Social Democratic Workers' Party (SDAP) and later co-founder of the Labour Party (PvdA) and historian who served as Prime Minister of the Netherlands from 7 August 1948 to 22 December 1958.
Drees was elected to the House of Representatives for the SDAP in the 1933 general election. He succeeded Willem Albarda as party leader in 1940 and, following the end of World War II, was appointed Deputy Prime Minister and Minister of Social Affairs in the national unity Schermerhorn–Drees cabinet. In February 1946, Drees was one of the co-founders of the Labour Party and became its first leader.