| William Mattus Vega | |
| Fullname: | William Mattus Vega |
| Birth Date: | 17 April 1964 |
| Birth Place: | Barva, Heredia, Costa Rica |
| League1: | Liga FPD |
| Role1: | Referee |
| Internationalyears1: | 2002 |
| Confederation1: | FIFA listed |
| Internationalrole1: | Referee |
William Mattus Vega (born April 17, 1964, in Barva, Heredia) is a Costa Rican former football referee, best known for supervising two matches during the 2002 FIFA World Cup held in Japan and South Korea.[1] As of 2022, Mattus is the last Costa Rican to officiate a match at a FIFA World Cup, as fellow countrymen have performed as assistant referees only.[2]