| Fred van der Blij | |
| Birth Date: | 13 May 1923 |
| Birth Place: | Leiden, Netherlands |
| Death Place: | Heino, Netherlands |
| Nationality: | Dutch |
| Fields: | Mathematics |
| Workplaces: | University of Utrecht |
| Alma Mater: | University of Leiden |
| Doctoral Advisor: | Hendrik Kloosterman |
| Doctoral Students: | Jan Hogendijk Jack van Lint |
Frederik van der Blij (13 May 1923, Leiden – 27 January 2018,[1] Heino, Netherlands) was a Dutch mathematician. From 1955 until his retirement in 1988 he was professor at the University of Utrecht. His research focused on number theory, among other fields.[2]