Bill, Billy, Willie or William Orr may refer to:

In activism or public service

• William Orr (United Irishman) (1766–1797), member of United Irishmen who was executed
• William Orr (Australian politician) (1843–1929), Australian politician and mining prospector
• Sir William Orr-Ewing, 2nd Bt. (1848–1903), son of Sir Archibald Orr-Ewing, 1st Baronet
• William Edwin Orr (1881–1965), American federal judge
• William Orr (trade unionist) (1900–1954), Australian coal miner and trade unionist
• Bill Orr (Nebraska first gentleman) (1935–2013), American insurance executive and Nebraska's only First Gentleman

In sports

• Willie Orr (1873–1946), Scottish football player and manager
• Willie Orr (footballer, born 1875) (1875–1912), footballer for Fulham F.C.
• Billy Orr (footballer) (1883–1963), Australian rules footballer
• Billy Orr (baseball) (1891–1967), Major League Baseball infielder
• Bill Orr, American racing driver in 1964 and 1965 Armstrong 500#Results
• Billy Orr (ice hockey) (born 1948), Canadian professional ice hockey defenceman
• Will Orr, New Zealand rally driver in 1992 World Rally Championship#Drivers' championship
• Bill Orr (football coach) (born 1983), Scottish Football Coach, Head of Performance Analysis for Stirling Albion Football Club

Other

• William Somerville Orr (before 1820–1873), English publisher and founder of William S Orr & Co.
• William McFadden Orr (1866–1934), British and Irish mathematician
• William Orr, American architect who built 1928 First Presbyterian Church (San Luis Obispo, California)
• William Orr, Scottish theatre director who immigrated to Australia and founded Phillip Street Theatre in 1953
• William T. Orr (1917–2002), American television producer
• William I. Orr (1919–2001), American amateur radio licensee and author

See also

• William Orr House, on National Register of Historic Places listings in LaPorte County, Indiana
• Billie Orr, American advocate for political and education reform since 1970