William John Sweeney (March 6, 1886 – May 26, 1948) was an American infielder in Major League Baseball from 1907 to 1914. He graduated from St. Xavier High School in Cincinnati in 1904.
In an eight year major-league career, he compiled a .272 batting average (1,004-3,692) with 442 runs scored, 11 home runs, 388 RBI, 172 stolen bases, an on-base percentage of .349 and a slugging percentage of .344. His best seasons were with the Boston Braves in 1911 and 1912, he hit .314 and .344 with 63 and 99 RBI respectively.