|Full name||Williams Guillermo Martínez Fracchia|
|Date of birth||18 December 1982|
|Place of birth||Montevideo, Uruguay|
|Date of death||17 July 2021(aged 38)|
|Height||1.85 m (6 ft 1 in)|
|2003||→ Ferro Carril (loan)|
|2006||→ West Brom (loan)||2||(1)|
|2008–2009||→ Reims (loan)||17||(0)|
|2010–2011||→ Chacarita Juniors (loan)||26||(0)|
|2014–2015||River Plate Montevideo||25||(1)|
|2017–2018||River Plate Montevideo||59||(4)|
|* Senior club appearances and goals counted for the domestic league only|
Martínez signed on loan for West Bromwich Albion of the Premier League in January 2006 until the end of the season, and made his Premier League debut as a half-time substitute against Fulham at Craven Cottage on 11 February 2006, a 6–1 defeat. He scored his first goal for the English club on 7 May 2006, an away game at Everton, also his first start for the club, while also conceding a late penalty that gave Everton a 2–2 draw.
In January 2008, he signed a two-and-a-half-year deal with Valenciennes, and was loaned to Reims for the 2008-09 season. On 17 August 2009, upon his request, he was released by Valenciennes and signed by his former club Defensor Sporting.
- "Everton 2–2 West Brom". BBC. 7 May 2006. Retrieved 30 November 2009.
- Comunicaciones, Compañia Chilena de. "Ex jugador de Palestino y Huachipato Williams Martínez falleció a los 38 años". alairelibre.cl (in Spanish). Retrieved 18 July 2021.
- Williams Martínez at National-Football-Teams.com
- tenfieldigital profile (in Spanish)
- Williams Martínez at Soccerbase
- Williams Martínez – French league stats at LFP – also available in French