Wílliam Ruben Martínez Carreras[1] (January 13, 1928 – December 28, 1997) was a Uruguayan footballer who played as a defender.

After playing for Nacional at various youth levels and for the first team he joined Racing Club de Montevideo in 1947.

In the last years of his playing career he worked as the player-manager of Fenix and Central Español.

Martínez was in the Uruguay squads for three FIFA World Cup tournaments (1950, 1954 and 1962).

Martínez won the Copa América with Uruguay in 1956,[3] he also played in three other editions of the tournament (1953,[4] 1955[1] and 1959A[5]).