Sir John Williams may refer to:

• Sir John Williams, 1st Baronet, of the City of London (1840-1926), Welsh baronet, physician and principal founder of the National Library of Wales
• Sir John Williams, Surveyor of the Navy (1700-1784), English naval architect
• General Sir John Williams KCB (1823-1911), British Royal Marines officer
• Sir John Williams, 2nd Baronet, of Eltham (1653-1723) English baronet and Member of Parliament
• Sir John Williams, 2nd Baronet, of Llangibby (1651-1704) Welsh baronet and Member of Parliament
• Sir John Williams (1675-1743) English merchant, Member of Parliament, and Lord Mayor of London
• Sir John Bickerton Williams (1792-1855) English nonconformist author and lawyer
• Sir John Hay Williams, 2nd Baronet, of Bodelwyddan (1794-1859) Welsh baronet and High Sheriff

• John Williams (disambiguation)

This disambiguation page lists articles associated with the title Sir John Williams.
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