Tiarks is a surname. Notable people with the surname include:
Frank Cyril Tiarks (1874–1952), British banker Geoffrey Lewis Tiarks (1909–1987), British Anglican bishop Henrietta Joan Tiarks (born 1940), later Henrietta Russell, Duchess of Bedford, British landowner and horse breeder who married the 14th Duke of Bedford Johann Ludwig Tiarks (1789–1837), German astronomer in British service, who surveyed the Canada–US border in the 19th century John Tiarks, (1903–1974), British Anglican bishop