Theunissen is a Dutch patronymic surname meaning "son of Theunis", a nickname for Anthonius. People with this surname include:
(1863–1918), French sculptor Elriesa Theunissen (born 1993), South African cricketer Gerald Theunissen (born 1933), American (Louisiana) politician and businessman James Theunissen (born 1981), English cricketer (1905–1979), Dutch archbishop of Malawi Marthinus Theunissen (1911–1983), South African sprinter Michael Theunissen (1932–2015), German philosopher Nicolaas Theunissen (1867–1929), South African cricketer and clergyman Werner Theunissen (1942–2010), Dutch composer and musician
Theunisse Gert-Jan Theunisse (born 1963), Dutch road racing cyclist
See also Teunissen Theunissen, a small town in South Africa Bill Theunissen Stadium