William McKinley (1843–1901) was the 25th president of the United States from 1897 to 1901.
William McKinley may also refer to:
- William McKinley (Virginia politician) (fl. 19th century), U.S. Representative from Virginia (1810–1811)
- William B. McKinley (1856–1926), U.S. Representative and Senator from Illinois
- William Laird McKinlay (1889–1983), author of his own survivor's account of the Last voyage of the Karluk
- William Michael McKinley (1879–1964), Speaker of the Illinois House of Representatives
- William Thomas McKinley (1938–2015), American composer and jazz pianist
- William McKinley Sr. (1807–1892), American manufacturer, father of President William McKinley
- Bill McKinley (1910–1980), American baseball umpire in the American League, 1946–1965
- Bill McKinley (footballer) (1882–1952), Australian rules footballer
- Bill McKinley (American football) (born 1949), American football player for the 1971 Buffalo Bills