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.