William Arnold may refer to:
Military William Richard Arnold (bishop) (1881–1965), U.S. Army chief of chaplains William Howard Arnold (general) (1901–1976), U.S. Army general
Politicians William Munnings Arnold (1819–1875), politician and speaker of the New South Wales Legislative Assembly William C. Arnold (1851–1906), U.S. representative from Pennsylvania William W. Arnold (1877–1957), U.S. representative from Illinois William Arnold (bailiff) (1903–1973), bailiff of Guernsey
Sports William Arnold (footballer) (1900–1977), English footballer Willie Arnold (1881–1957), Welsh rugby international player
Others William Arnold (settler) (1587–1676), founding settler in Rhode Island William Arnold (master mason) (fl. 1595–1637), master mason in Somerset, England William Delafield Arnold (1828–1859), British author and colonial administrator William W. Arnold (ornithologist) (1843–1923), American physician and ornithologist William Thomas Arnold (1852–1904), English writer and journalist William A. Arnold (1904–2001), American plant physiologist and biophysicist William Howard Arnold (physicist) (fl. 1955–2004), American nuclear physicist William Arnold (film critic), American journalist, author and film critic
See also RNLB Sir William Arnold (ON 1025), former RNLI lifeboat in Guernsey Bill Arnold (disambiguation) Billy Arnold (disambiguation) William Arnaud (disambiguation)