Gillen is a surname. Notable people with the surname include:
Aidan Gillen (born 1968), actor Ann Gillen, artist Brian Gillen (born 1970), member of the Irish Republican Army Charles P. Gillen (1876–1956), mayor of Newark, New Jersey, US Dolores Gillen (1914/1915–1947), American actress Francis James Gillen (1855–1912), Australian anthropologist and ethnologist Gerard Gillen, professor of music Gwen Gillen (1941–2017), American artist Kieron Gillen (born 1975), journalist and comic book writer Laura Gillen (born 1969), New York politician Mary A. Gillen (1894–1963), New York politician Michael J. Gillen (1885–1942), New York politician Pete Gillen (born 1947), American college basketball coach and television commentator Peter Paul Gillen (1858–1896), storekeeper and politician in South Australia Ray Gillen (1959–1993), singer with various bands, among them Black Sabbath Shelley Gillen, Canadian producer and screenwriter Simon Gillen (1855–1918), Wisconsin, US politician and judge Cathy Gillen Thacker, American author of romance novels