Felix Thaddeus Mackiewicz (November 20, 1917 – December 20, 1993) was an American professional baseball outfielder. He played in Major League Baseball (MLB) from 1941 through 1947 for the Philadelphia Athletics, Cleveland Indians, and Washington Senators. Altogether, he appeared in 223 big-league games and collected 174 hits, including 32 doubles and 12 triples. He concluded his professional career during the 1949 minor league season.