Dionysius Adrianus Petrus Norbertus Koolen (21 January 1871 – 24 March 1945) was a Dutch politician of the defunct Roman Catholic State Party (RKSP), later formed to the Catholic People's Party (KVP) now merged into the Christian Democratic Appeal (CDA).

[1] He was a member of the General League of Roman Catholic Caucuses and its continuation, the Roman Catholic State Party.

He was a member of the House of Representatives of the Netherlands from 1905 until 1925, when he became minister of Labour, Trade and Industry, which was a single ministry at the time.

He was speaker of the House of Representatives of the Netherlands in the period from 14 October 1920 to 5 August 1925.

This article about a Dutch politician is a stub.