Bill Hallahan, American baseball player (d. 1981)
William Anthony Hallahan (August 4, 1902 – July 8, 1981) was an American left-handed pitcher in Major League Baseball during the 1920s and 1930s. Nicknamed "Wild Bill" because of his lack of control on the mound—he twice led the National League in bases on balls—Hallahan nevertheless was one of the pitching stars of the 1931 World Series and pitched his finest in postseason competition.

Hallahan also was the starting pitcher for the National League in the first All-Star Game in 1933, losing a 4–2 decision to Lefty Gomez of the American League and surrendering a third-inning home run to Babe Ruth in the process.