Isaäc Arend "Iek" Diepenhorst (18 July 1916 – 21 August 2004) was a Dutch politician of the defunct Anti-Revolutionary Party (ARP) and later the Christian Democratic Appeal (CDA) party and jurist.

The Cabinet Cals fell just one year later on 14 October 1966 and continued to serve in a demissionary capacity until it was replaced by the caretaker Cabinet Zijlstra with Diepenhorst continuing as Minister of Education and Sciences, taking office on 22 November 1966.

In January 1971 Diepenhorst announced that he wouldn't stand for the election of 1971 but wanted tot return to the Senate.

Diepenhorst also became active in the public sector occupying numerous seats as a nonprofit director on several boards of directors and supervisory boards (Royal Academy of Arts and Sciences, Netherlands Bible Society, Bartiméus Foundation and the Utrecht University) and served on several state commissions]] and councils on behalf of the government (Education Council, Probation Agency and the Council for Culture).

This article about a Dutch Christian Democratic Appeal politician is a stub.