Kosy was formerly part of the German Empire. In the German Empire, the place was called Quossen.
The place is now called Kosy and belongs to Poland.
| Historical place name | Country | Administration | Time |
|---|---|---|---|
| Quossen | German Empire | Bartenstein (Ostpr.) | 1939 |
| Kosy | Under Polish administration | Bartoszyce | 1945 |
| Kosy | Poland | Olsztyn | 1992 |