Dr. Quartus de Wet (1899–1980), South African judge-president of the high court of the Transvaal.
Born in 1899 in Pretoria, he was the son of Nicolaas Jacobus de Wet, Chief Justice of South Africa and acting Governor-General and Ella Scheepers (his first wife), who is reputed to have composed the popular Afrikaans song Sarie Marais during the Anglo-Boer War.
He obtained a law degree in 1922 and was admitted as an advocate (the South African equivalent of a barrister) to the bar of Pretoria the same year. He became a judge of the Transvaal in 1950, and he became the judge president of the high court of the Transvaal in 1961.
He is famous for presiding over the 1963 Rivonia Trial of Nelson Mandela and other anti-apartheid activists. During the Rivonia Trial, De Wet sentenced Mandela and other anti-apartheid activists to life imprisonment instead of a possible death sentence, for sabotage as a result of the trial. He retired in 1969.