Frank Bissell "Lefty" Killen (November 30, 1870 – December 3, 1939) was a professional baseball player. He was a left-handed pitcher over parts of ten seasons (1891–1900) with the Milwaukee Brewers, Washington Senators (NL), Pittsburgh Pirates, Boston Beaneaters and Chicago Orphans. He was born and later died in Pittsburgh, Pennsylvania, at the age of 69.

Career

In 1893, Killen posted a league-best 36 victories against fourteen defeats. No left-hander in National League history has won as many games since then. He was the National League wins leader in 1893 and 1896 with Pittsburgh, leading the league in complete games and shutouts in 1896. For his career, he compiled a 164–131 record in 321 appearances, with a 3.78 ERA and 725 strikeouts. As a hitter, Kileen posted a career .241 batting average (241-for-998) with eleven home runs, 127 RBI, 151 runs scored and drew 131 bases on balls.