Jacobus Gideon Nel Strauss, known as Koos Strauss, Kosie Strauss or J. G. N. Strauss (Calvinia, Northern Cape 1900-?), was leader of the South African United Party from 1950 to 1956. He was preceded by Jan Smuts. In the 1953 election, the United Party under Strauss lost seven seats while their opponents the National Party gained twenty-five more seats and a majority in Parliament. Following this election, the United Party suffered two splits, creating the Liberal Party and the Union Federal Party.
In 1954, a further split resulted in the National Conservative Party. In 1956, while plagued by ill health and convalescing in England, he asked his party to decide whether they wished to keep him on as leader. They declined to do so: the first time the leader of a South African political party had been forcibly removed. Strauss was succeeded as United Party leader by De Villiers Graaff. |}