Johannes Gerard Adolph Diergaardt, more commonly known as Hans Diergaardt (16 September 1927 – 13 February 1998) was a Namibian politician active for nearly a decade after Namibia gained independence. Prior to that, he was elected as the fifth Kaptein of the then-autonomous Baster community at Rehoboth, succeeding Dr. Ben Africa in 1979 after winning a court challenge to the disputed election of 1976.
Both before and after independence, Diergaardt founded several local political parties, among them the Federal Convention of Namibia. He represented this party as a member of the Constituent Assembly of Namibia, convened to draft the constitution for the new nation of Namibia.
Diergaardt is known for his criticism of black-majority rule in the early years of independent Namibia. Believing that minority group rights were not sufficiently protected, he led a legal suit to establish autonomy for Rehoboth Gebied, the historic district of Baster settlement, which had a kind of autonomy under German colonial and South African rule. The nation's Supreme Court ruled that Rehoboth had no special status in the newly independent Namibia. Before his death, Diergaardt filed an official complaint in 1998 with the United Nations Human Rights Committee, which ruled in 2000. It declined to rule on one issue, but concluded that Namibia was exercising linguistic discrimination against the Afrikaans-speaking Basters.
Diergaardt was born into a Baster family in Rehoboth, then part of South-West Africa, on 16 September 1927. He became a professional car mechanic but also worked as a farmer, businessman, and politician throughout his life.
In 1947 Diergaardt started his political career by joining the Rehoboth Burgervereniging (English: Rehoboth Citizen Association). He later founded the Rehoboth Tax Payers Association (1959), the Rehoboth Volksparty (English: Rehoboth Peoples' Party, 1968), and the Rehoboth Liberation Party (1975). This was during the period following World War I when South African administered the territory, although the United Nations General Assembly had retracted its mandate in 1966. After that, SWAPO initiated an independence movement in 1966, conducting a guerrilla war against South Africa.