| Gaoussou Youssouf Siby | |
| Birth Date: | 2000 4, df=yes |
| Height: | 1.77 m |
| Position: | Defender |
| Currentclub: | Hafia FC |
| Clubnumber: | 10 |
| Youthyears1: | ?–2021 |
| Youthclubs1: | Wakriya AC |
| Years1: | 2021–2022 |
| Clubs1: | Wakriya AC |
| Caps1: | 8 |
| Goals1: | 6 |
| Years2: | 2022– |
| Clubs2: | Hafia FC |
| Nationalyears1: | 2021– |
| Nationalteam1: | Guinea |
| Nationalcaps1: | 2 |
| Nationalgoals1: | 1 |
Gaoussou Youssouf Siby (born 15 April 2000) is a Guinean professional footballer who plays as a defender for the Guinée Championnat National club Hafia FC and the Guinea national team.