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]