| Willem van der Kaay | |
| Birth Name: | Willem van der Kaaij |
| Birth Date: | 5 May 1831 |
| Birth Place: | Alkmaar, Netherlands |
| Death Date: | 29 July 1918 |
| Death Place: | The Hague, Netherlands |
| Nationality: | Dutch |
| Occupation: | judge, politician |
Willem van der Kaay (originally van der Kaaij) (5 May 1831 – 29 July 1918) was a Dutch judge and liberal politician. He was a member of the House of Representatives for Alkmaar from 1875 to 1894, and served as Minister of Justice in Joan Röell's cabinet from 1874 to 1879.