Johannes "Jan" de Klerk, DMS (22 July 1903 – 24 January 1979[1]) was a South African politician.

As a member of the National Party, de Klerk served as interim State President for nine days following the retirement of Jacobus Johannes Fouché in 1975.

In 1968, he was directly involved in the Mafeje affair as he opposed the hiring of Archie Mafeje as a senior lecturer to University of Cape Town (UCT) telling the UCT Council about the[3][4]government’s intense displeasure at the decision to appoint an African, which is tantamount to flouting the accepted traditional outlook of South Africa.

Should your Council disregard my appeal and give effect to this decision, the government will not hesitate in taking such action as it may deem fit to ensure that the tradition referred to above is observedBy the time of his retirement from the cabinet, de Klerk had been a cabinet minister for more than fifteen years and was rewarded with the Decoration for Meritorious Services.

He retired from political life, spent his last few years on a farm and died in Krugersdorp on 24 January 1979.