| Guðmundur Reynir Gunnarsson | |
| Fullname: | Guðmundur Reynir Gunnarsson |
| Birth Date: | 1989 1, df=yes |
| Birth Place: | Iceland |
| Position: | Left back |
| Youthclubs1: | KR |
| Years1: | 2006–2008 |
| Years2: | 2008–2009 |
| Years3: | 2009–2015 |
| Years4: | 2015 |
| Clubs4: | → Víkingur Ólafsvík (loan) |
| Caps1: | 42 |
| Caps2: | 4 |
| Caps3: | 98 |
| Caps4: | 22 |
| Goals1: | 3 |
| Goals2: | 0 |
| Goals3: | 5 |
| Goals4: | 0 |
| Nationalyears1: | 2005 |
| Nationalteam1: | Iceland U-17 |
| Nationalcaps1: | 7 |
| Nationalgoals1: | 3 |
| Nationalyears2: | 2007–2008 |
| Nationalteam2: | Iceland U-19 |
| Nationalcaps2: | 9 |
| Nationalgoals2: | 3 |
| Nationalyears3: | 2008–2011 |
| Nationalteam3: | Iceland U-21 |
| Nationalcaps3: | 3 |
| Nationalgoals3: | 0 |
| Nationalyears4: | 2008–2010 |
| Nationalteam4: | Iceland |
| Nationalcaps4: | 3 |
| Nationalgoals4: | 0 |
Guðmundur Reynir Gunnarsson (born 21 January 1989) is a retired Icelandic football player who mostly played as a left back for Icelandic football club KR.