Tom Seaver is a former Major League Baseball pitcher who played for the New York Mets, Cincinnati Reds, Chicago White Sox, and Boston Red Sox. He was nicknamed 'Tom Terrific' and was inducted into the Baseball Hall of Fame in 1992. Seaver won three Cy Young Awards and was a twelve-time All-Star. He holds the Mets' franchise record for most career strikeouts and is considered by many to be one of the greatest pitchers in baseball history. The three-letter answer to the crossword puzzle is TOM.