William Arnold
William Arnold may refer to:
Military
- William [Richard Arnold (bishop)], U.S. Army chief of chaplains
- William Howard Arnold (general), U.S. Army general
Politicians
- William Munnings Arnold, politician and speaker of the New South Wales Legislative Assembly
- William C. Arnold, U.S. representative from Pennsylvania
- William W. Arnold, U.S. representative from Illinois
- William Arnold (bailiff), bailiff of Guernsey
Sports
- William Arnold (footballer), English footballer
- Willie Arnold, Welsh rugby international player
Others
- William Arnold (settler), founding settler in Rhode Island
- William Arnold (master mason), master mason in Somerset, England
- William Delafield Arnold, British author and colonial administrator
- William W. Arnold (ornithologist), American physician and ornithologist
- William Thomas Arnold, English writer and journalist
- William Howard Arnold (physicist), American nuclear physicist
- William Arnold (film critic), American journalist, author and film critic