| Gerard Nijboer | |
| Headercolor: | lightsteelblue |
| Fullname: | Gerhardus Marinus Maria Nijboer |
| Birth Date: | 18 August 1955 |
| Birth Place: | Hasselt, Overijssel, Netherlands |
| Weight: | 700NaN0 |
| Country: | Netherlands |
| Sport: | Athletics |
| Event: | Marathon |
| Show-Medals: | yes |
Gerhardus Marinus Maria Nijboer (pronounced as /nl/; born 18 August 1955) is a former Dutch long-distance runner. Nijboer competed in three consecutive Summer Olympics, starting in 1980 (Moscow, Soviet Union), when he won the silver medal in the marathon. He became European champion in the marathon in 1982, for which he was named Dutch Sportsman of the year.
His personal best time was 2:09:01 at the Amsterdam Marathon of 26 April 1980, which was at the time the second best marathon ever (after Derek Clayton's 2:08:34 run in 1969).