Siedlec was formerly part of the German Empire. In the German Empire, the place was called Schädlitz.
The place is now called Siedlec and belongs to Poland.
| Historical place name | Country | Administration | Time |
|---|---|---|---|
| Siedlec | German Empire | Gostyn | before the Versailles Treaty |
| Siedlec | Poland | Gostyń | after the Versailles Treaty |
| Schädlitz | German Empire | Gostingen | 1939 |
| Siedlec | Poland | Gostyń | 1945 |
| Siedlec | Poland | Leszno | 1992 |