| Duško Ajder | |
| Fullname: | Dušan Ajder |
| Birth Date: | 6 December 1958 |
| Birth Place: | Belgrade, SFR Yugoslavia |
| Position: | Centre back |
| Years1: | 1976–1979 |
| Years2: | 1979–1991 |
| Years3: | 1991–1992 |
| Years4: | 1992–1994 |
| Clubs1: | Red Star Belgrade |
| Clubs2: | Rad |
| Clubs3: | Ankaragücü |
| Clubs4: | Leça |
| Caps1: | 1 |
| Caps2: | 255 |
| Caps3: | 6 |
| Caps4: | 35 |
| Goals1: | 0 |
| Goals2: | 20 |
| Goals3: | 0 |
| Goals4: | 2 |
Dušan "Duško" Ajder (; born 6 December 1958) is a Serbian retired footballer who played as a central defender.
Born in Belgrade, SR Serbia, he played for Belgrade clubs Red Star and FK Rad in the Yugoslav First League before moving abroad, first to Turkey, to play with Ankaragücü[1] and then to Portugal to play with Leça.[2]