Anthony John "A. J." Pierzynski (pronounced /pɪərˈzɪnski/) (born December 30, 1976 in Bridgehampton, New York) is an American Major League Baseball catcher who has played for the Chicago White Sox since 2005. Pierzynski formerly played with the Minnesota Twins (1998-2003) and San Francisco Giants (2004). Pierzynski was also a wrestler for Total Nonstop Action Wrestling.

Anthony John Pierzynski was born December 30, 1976, in Bridgehampton, New York. He attended Dr. Phillips High School in Orlando, Florida, where he won All-State honors in baseball. New York Yankees outfielder Johnny Damon was one of Pierzynski's high school teammates. Pierzynski graduated high school in 1994 and also signed a letter of intent to play baseball at the University of Tennessee. He was also drafted by the Minnesota Twins that year, and he chose to join the Twins. He began his minor league career with the Gulf Coast League Twins and spent the next four years playing for the minor-league Elizabethton Twins, Fort Wayne Wizards, Fort Myers Miracle, New Britain Rock Cats, and Salt Lake Buzz.

Pierzynski was drafted by the Minnesota Twins on June 2, 1994, out of high school. After four years in the Twins organization, he was called up to the Major League team, and made his debut on September 9, 1998. He spent the next five seasons, through the 2003 season, with Minnesota, though he was not a regular starter until 2001. From 1998-2000, he appeared in just 49 games for the Twins. In 2002 he made the American League All-Star Team as a reserve catcher. In the 2002 American League Division Series, Pierzynski hit an important home run in the ninth inning of the final game, in which the Twins clinched the series. In 2003, Pierzynski reached a .312 batting average, a career high that still stands.