Pieter Jacobus Oud (5 December 1886 – 12 August 1968) was a prominent liberal Dutch politician who served held numerous political offices, including member of the House of Representatives, Minister of Finance and Mayor of Rotterdam. He was a founding member of the Dutch Labour Party (PvdA) and the People's Party for Freedom and Democracy (VVD). Before the war he was member of the left-liberal Freethinking Democratic League (VDB).
Oud came from a middle-class family, his father traded in tobacco, wine and, later, stocks and served as alderman in Purmerend. Oud attended HBS in Amsterdam graduating in 1904. He continued to study to become notary between 1904 and 1907. During this time he had become member of the board of the League of Freethinking Propaganda Associations, the freethinking liberal youth organisation. He took a private courses in registration in Gorinchem between 1907 and 1909. Between 1909 and 1911 he was civil servant within the ministry of Finance responsible for registration and government possessions. In 1911 he became a tax collector on Texel. In 1912 he took his matriculation in order to study law at the University of Amsterdam. He combined his work as tax collector with his study of law. In the same year he married Johanna Cornelia Fischer, from this marriage they got one son. In 1914 he became tax collector in Ommen. Meanwhile, he was mobilized as Sergeant of the seventh regiment infantry, which was stationed near Amsterdam between 1914 and 1916. Between 1915 and 1919 he was member of the national board of the VDB. He graduated in 1917 on basis of a disputation.