Guillermo Antonio Quiroz (Spanish pronunciation: [ɡiˈʝeɾmo kiˈɾos]; born November 29, 1981) is a Venezuelan former professional baseball catcher and current manager of the Winston-Salem Dash, the High-A affiliate of the Chicago White Sox.

He has played in Major League Baseball (MLB) for the Toronto Blue Jays, Seattle Mariners, Texas Rangers, Baltimore Orioles, Boston Red Sox and San Francisco Giants.

[8] The broken hand and torn arm muscle he suffered in 2004 hurt his chances of taking over as the Blue Jays' starting catcher in 2005.

[13] Quiróz started the seventh game of the 2006 season for the Mariners, but was outrighted to Triple-A Tacoma Rainiers eight days later.

[19][20] He was invited to spring training and expected to compete for the backup catcher position at the start of the 2009 season,[21][22] but was released on March 21.

[30] He was invited to spring training to be the backup to Nick Hundley,[31] but did not win the job and spent the season playing for the Tucson Padres.

[36] According to the International League transactions page, Quiróz was outrighted to the Pawtucket Red Sox on October 10, but chose to become a free agent.

[37] On November 20, 2012, He signed a minor league deal with an invite to spring training with the San Francisco Giants.

[38] On May 4, 2013 Quiróz hit his first career walk-off home run, a tenth inning, pinch-hit homer against former battery mate Brandon League of the Los Angeles Dodgers, leading the Giants to a 10–9 victory.

On February 12, 2016, Quiróz signed a minor league contract with the Cleveland Indians that included an invitation to spring training.

[49] In January 2020, he was named manager of the Kannapolis Cannon Ballers, the Single-A affiliate of the Chicago White Sox.