Gielen
Gielen is the family name of the following people:
- Carl Gielen (1900–1987), Roman Catholic priest and Provost of Cologne Cathedral
- Frans Gielen (1921-2004), Belgian racing cyclist
- Franz Gielen (1867–1947), Lord Mayor of the Rhineland
- Johan Gielen (* 1968), Belgian DJ and music producer
- Josef Gielen (1890–1968), Austrian actor
- Katrien Gielen (* 1990), Belgian volleyball and beach volleyball player
- Marlis Gielen (* 1959), German Catholic theologian
- Michael Gielen (1927–2019), Austrian conductor and composer
- Michael Andrew Gielen (* 1971), New Zealand clergyman and Roman Catholic auxiliary bishop in Auckland
- Victor Gielen (1825–1887), German cigar manufacturer, tobacco dealer and member of the Reichstag