Nyhan is a surname. Notable people with the surname include:
Brendan Nyhan (born 1978), American liberal to moderate political blogger, author, and political columnist David Nyhan (1940–2005), American journalist Denis Nyhan (1939–2021), New Zealand driver of standardbred racehorses at premier racing events William Nyhan (1926–2026), American physician
See also Lesch–Nyhan syndrome (LNS), a rare, inherited disorder caused by a deficiency of the enzyme hypoxanthine-guanine phosphoribosyltransferase Sakati–Nyhan–Tisdale syndrome, a rare genetic disorder associated with abnormalities in the leg bones, congenital heart defects and craniofacial defects