William Armstrong
William Armstrong may refer to:
- Kinmont Willie Armstrong (fl. 16th century), Scottish border reiver, known as "Kinmont Willie"
- William Armstrong (Christie's Will) (1602?–1658?), Scottish border freebooter, known as "Christie's Will"
- William Armstrong (artist) (1822–1914), Canadian artist
- William Armstrong (Virginia) (1782–1865), U.S. Representative from Virginia
- William H. Armstrong (1914–1999), author of the children's book Sounder
- William Hepburn Armstrong (1824–1919), U.S. Representative from Pennsylvania
- William L. Armstrong (born 1937), U.S. Senator from Colorado
- William Armstrong, 1st Baron Armstrong (1810–1900), British industrialist
- William Armstrong, Baron Armstrong of Sanderstead (1915–1980), British civil servant
- William Armstrong (detective), detective on the Zodiac Killer case
- William Armstrong, American automobile inventor and founder of Armstrong Electric
- William "Duff" Armstrong (1833–1889), 1858 defendant for the murder of James Preston Metzker in Mason County, Illinois
- William T. Armstrong (1929–2005), Canadian Broadcasting Corporation executive
- William W. Armstrong (journalist) (1806–1878), U.S. journalist and politician from Ohio
- William W. Armstrong (1864–1944), U.S. lawyer and politician in New York state
- William Ward Armstrong, a Canadian mathematician and computer scientist.
- William Armstrong (footballer) (born 1892), Australian rules footballer
- William Armstrong (music critic) (1858–1942), American music critic
- Billy Armstrong (born 1943), politician in Northern Ireland
- Bill Armstrong (coach), American college football coach
- Bill Armstrong (ice hockey b. 1966), ice hockey player
- Bill Armstrong (ice hockey b. 1970), ice hockey player and coach
- Bill Armstrong (footballer) (1913–1995), footballer
- Bill Armstrong (announcer), game show announcer