Gerhardus Willem Koornhof (born 1951 or 1952) is a South African politician and economist who serves as the Parliamentary Counsellor to President Cyril Ramaphosa.

When Ramaphosa served as deputy president, Koornhof was his parliament counsellor.

Koornhof left the NNP and joined Bantu Holomisa's United Democratic Movement.

[2] Koornhof resigned from the UDM in 2003 and joined the African National Congress.

He was Whip for the Study Group on Public Enterprises & Ethics and Members’ Interests between 2009 and 2014 and served on the ANC Provincial Executive Committee in Gauteng between 2010 and 2018.