Fernando Gabriel Tatís Medina Sr. is a Dominican former professional baseball third baseman. Over his 11-year Major League Baseball (MLB) career, Tatís played for the Texas Rangers, St. Louis Cardinals, Montreal Expos, Baltimore Orioles, and New York Mets. He holds the major league record for runs batted in (RBI) in an inning, a feat that he achieved by hitting two grand slams in one inning during a game on April 23, 1999, becoming the only player in MLB history to do so. His son, Fernando Jr., plays for the San Diego Padres.

A run batted in or runs batted in (RBI) is a statistic in baseball and softball that credits a batter for making a play that allows a run to be scored. For example, if the batter bats a base hit which allows a teammate on a higher base to reach home and so score a run, then the batter gets credited with an RBI.