| Theo Gerdner | |
| Birth Date: | 19 March 1916 |
| Birth Place: | Cape Town, Cape Province, Union of South Africa |
| Death Place: | Pretoria, Gauteng, South Africa |
| Party: | National Party (before 1973) |
| Otherparty: | Democratic Party (1973–1977)[1] New Republic Party (1977)[2] |
| Office: | Minister of the Internal Affairs |
Theodor Johannes Adolph Gerdener (19 March 1916 – 21 November 2013) was a South African politician and author.
Born in Cape Town, Gerdener served as an interior minister for the National Party. He resigned from the National Party, and founded and chaired the Democratic Party from 1973 to 1977. He was Administrator of the Natal Province between November 1961 and August 1970.
Theo Gerdener died on 21 November 2013, aged 97, in Pretoria.[3]