| Lennik | |
| Picture-Legend: | Lennik's town hall |
| Map: | Lennik Flemish-Brabant Belgium Map.svg |
| Map-Legend: | Location of Lennik in Flemish Brabant |
| Arms: | Blason Lennik.svg |
| Flag: | Lennik vlag.svg |
| Arrondissement: | Halle-Vilvoorde |
| Nis: | 23104 |
| Mayor: | Irina De Knop (LB) |
| Majority: | LB, CD&V, Groen |
| Postal-Codes: | 1750 |
| Telephone-Area: | 02, 054 |
| Web: | www.lennik.be |
| Coordinates: | 50.8°N 13°W |
Lennik (in Dutch; Flemish pronounced as /ˈlɛnɪk/) is a municipality located in the Belgian province of Flemish Brabant. The municipality comprises the towns of Sint-Kwintens-Lennik, Sint-Martens-Lennik, Eizeringen and Gaasbeek. It is also situated in the Pajottenland. On January 1, 2006, Lennik had a total population of 8,694. The total area is 30.80 km2 which gives a population density of 282 inhabitants per km2.
On its territory is the national Gaasbeek Castle museum.A 4 metre high statue of Prince (a traditional plough horse) stands on the Market Place.