Theunissen is a Dutch patronymic surname meaning "son of Theunis", a nickname for Anthonius.[1] People with this surname include:
Corneille Theunissen (1863–1918), French sculptorElriesa Theunissen (born 1993), South African cricketerGerald Theunissen (born 1933), American (Louisiana) politician and businessmanJames Theunissen (born 1981), English cricketerMarthinus Theunissen (1911-1983), South African sprinterMichael Theunissen (born 1932), German philosopherNicolaas Theunissen (1867–1929), South African cricketerWerner Theunissen (1942-2010), Dutch composer and musicianTheunisseGert-Jan Theunisse (born 1963), Dutch road racing cyclist