| Nikolai Rehnen | |
| Birth Date: | 1997 2, df=yes |
| Birth Place: | Cologne, Germany |
| Height: | 1.91 m |
| Position: | Goalkeeper |
| Currentclub: | SV Sandhausen |
| Clubnumber: | 1 |
| Youthclubs1: | SpVg Steinhagen |
| Youthyears2: | 2007–2015 |
| Youthclubs2: | Arminia Bielefeld |
| Years1: | 2015–2021 |
| Clubs1: | Arminia Bielefeld |
| Caps1: | 0 |
| Goals1: | 0 |
| Years2: | 2015–2017 |
| Clubs2: | Arminia Bielefeld II |
| Caps2: | 41 |
| Goals2: | 0 |
| Years3: | 2018–2019 |
| Clubs3: | → Fortuna Köln (loan) |
| Caps3: | 37 |
| Goals3: | 0 |
| Years4: | 2019–2020 |
| Clubs4: | → Alemannia Aachen (loan) |
| Caps4: | 0 |
| Goals4: | 0 |
| Years5: | 2021– |
| Clubs5: | SV Sandhausen |
| Caps5: | 39 |
| Goals5: | 0 |
| Nationalyears1: | 2016–2017 |
| Nationalteam1: | Germany U20 |
| Nationalcaps1: | 2 |
| Nationalgoals1: | 0 |
| Club-Update: | 22 May 2024 |
Nikolai Rehnen (born 4 February 1997) is a German professional footballer who plays as a goalkeeper for 3. Liga side SV Sandhausen.[1]