William Ferreira Martínez (born February 25, 1983, in Artigas) is a Uruguayan football striker.
Ferreira began his footballing career with Uruguayan giant Nacional, where he was part of a national title in 2002.
His presence was fundamental as he scored 16 goals in 21 games; becoming the league top scorer and helping the club in adding another championship trophy to its showcase.
In the Clausura 2009, he also finished in the top of the list with 9 goals, and netted 4 more in the playoffs stage, totalling 29 for the year.
On 31 January 2011 makes official its assignment with option to buy the Spanish club Real Valladolid of Spanish football but FIFA rejected the international transfer after the TAS rejected the interim suspension as the player returned to Bolívar until further notice.