Dillen is a Dutch surname, and is a variant of the Breton word Dillon and means faithful. Notable people with the surname include:
Coen Dillen (1926–1990), Dutch footballer Cor Dillen (1920–2009), Dutch businessman, former billionaire Philips CEO Jacques Dillen (1903–?), Belgian wrestler Karel Dillen (1925–2007), Belgian politician Ken Dillen (1938–2020), Canadian politician René Dillen (born 1951), Belgian racing cyclist
See also Dillens