| Mathieu Barrau | |
| Birth Place: | Beaumont-de-Lomagne, France |
| Birth Date: | 3 September 1977 |
| Weight: | 79kg (174lb) |
| Position: | scrum half |
| Repteam1: | France |
| Repyears1: | 2004 |
| Repcaps1: | 3 |
| Amatyears1: | 1995-1997 |
| Amatyears2: | 1997-1999 |
| Amatyears3: | 1999-2005 |
| Amatyears4: | 2005-2006 |
| Amatyears5: | 2006- |
| Amatteam1: | Stade Toulousain |
| Amatteam2: | USAP |
| Amatteam3: | SU Agen |
| Amatteam4: | Castres |
| Amatteam5: | SU Agen |
Mathieu Barrau (born 3 September 1977 in Beaumont-de-Lomagne, France is a French international rugby union scrum half principally for SU Agen.
Barrau made his international début for France in July 2004, against usa, but would have to fight with Pierre Mignoni, Dimitri Yachvili, Frédéric Michalak but mostly Jean-Baptiste Élissalde for the France number 9 shirt. .