| Constantin Reiner | |
| Birth Date: | 1997 7, df=yes |
| Birth Place: | Oberndorf bei Salzburg, Austria |
| Currentclub: | Piast Gliwice |
| Clubnumber: | 37 |
| Position: | Centre-back |
| Youthyears1: | 2002–2006 |
| Youthclubs1: | USK Obertrum |
| Youthyears2: | 2006–2014 |
| Youthclubs2: | Red Bull Salzburg |
| Years1: | 2014–2018 |
| Clubs1: | USK Anif |
| Caps1: | 84 |
| Goals1: | 3 |
| Years2: | 2018–2022 |
| Clubs2: | SV Ried |
| Caps2: | 80 |
| Goals2: | 5 |
| Years3: | 2022– |
| Clubs3: | Piast Gliwice |
| Caps3: | 18 |
| Goals3: | 2 |
| Years4: | 2023–2024 |
| Clubs4: | → Rheindorf Altach (loan) |
| Caps4: | 23 |
| Goals4: | 0 |
| Pcupdate: | 26 May 2024 |
Constantin Reiner (born 11 July 1997) is an Austrian professional footballer who plays as a centre-back for Polish club Piast Gliwice.
For the 2023–24 season, Reiner joined Rheindorf Altach on loan with an option to buy.[1]