| Giel Deferm | |
| Fullname: | Giel Deferm |
| Birth Date: | 30 June 1988 |
| Birth Place: | Sint-Truiden, Belgium |
| Height: | 1.79 m |
| Position: | Left back |
| Currentclub: | Thes Sport |
| Clubnumber: | 26 |
| Youthyears1: | 1995–1997 |
| Youthclubs1: | VK Zepperen |
| Youthyears2: | 1997–2006 |
| Youthclubs2: | Sint-Truiden |
| Years1: | 2006–2014 |
| Clubs1: | Sint-Truiden |
| Caps1: | 138 |
| Goals1: | 2 |
| Years2: | 2013 |
| Clubs2: | → Beerschot (loan) |
| Caps2: | 10 |
| Goals2: | 0 |
| Years3: | 2014–2018 |
| Clubs3: | Lommel United |
| Caps3: | 44 |
| Goals3: | 0 |
| Years4: | 2018– |
| Clubs4: | Thes Sport |
| Caps4: | 57 |
| Goals4: | 5 |
| Pcupdate: | 25 November 2020 |
Giel Deferm (born 30 June 1988) is a Belgian footballer who plays as a left back, who plays for Thes Sport in the Belgian First Amateur Division.