William Borthwick
William Borthwick may refer to:
- William Borthwick (Canadian politician), mayor of Ottawa, 1895–1896
- Bill Borthwick, Australian politician
- William Borthwick, 1st Lord Borthwick, Scottish peer and ambassador
- William Borthwick, 2nd Lord Borthwick, Scottish ambassador to England
- William Borthwick, 3rd Lord Borthwick, Scottish nobleman and ambassador
- William Borthwick, 4th Lord Borthwick, Scottish nobleman
- William Borthwick (Dorset politician), British Army Captain and barrister
- William Jason Maxwell Borthwick, British barrister and Royal Naval Volunteer Reserve officer
- William Borthwick (surgeon), Scottish surgeon