William Buchan may refer to:
William Buchan (physician) (1729–1805), Scottish physician William Buchan, 3rd Baron Tweedsmuir (1916–2008), English peer and author Bill Buchan Sr., Scottish-born American sailor and boat-builder William Earl Buchan (born 1935), American sailor and Olympic champion William Carl Buchan (born 1956), his son, American sailor and Olympic champion Willie Buchan (1914–2003), Scottish footballer