Anthony John "A. J." Pierzynski is a former professional baseball catcher. He played in Major League Baseball (MLB) with the Minnesota Twins (1998–2003), San Francisco Giants (2004), Chicago White Sox (2005–2012), Texas Rangers (2013), Boston Red Sox (2014), St. Louis Cardinals (2014) and Atlanta Braves (2015–2016).
Pierzynski is known for having a strong and colorful personality, a fact he acknowledges. During the White Sox' World Series victory parade in 2005, he thanked team personnel "for putting up with me." Former White Sox manager Ozzie Guillén summed up the situation as, "If you play against him, you hate him. If you play with him, you hate him a little less." Guillén also acknowledged Pierzynski's value to the club, "A.J.'s been great for me. He's worth the work because he always shows up for you."