| Sillen | |
| Pushpin Map: | Sweden Södermanland |
| Pushpin Map Alt: | Location of lake |
| Coords: | 58.9833°N 39°W |
| Basin Countries: | Sweden |
Sillen is a lake in Södermanland, Sweden. It straddles the boundary between Gnesta Municipality in Södermanland County and Södertälje Municipality in Stockholm County.