Alexander Johnston may refer to:
- Alexander Johnston (businessman) (1774âÂÂ1864), Scottish mill owner
- Alexander Johnston (1775âÂÂ1849), British colonial official and orientalist in Ceylon
- Alexander Johnston (Scottish politician) (1790âÂÂ1844)
- Alexander Keith Johnston (1804âÂÂ1871), Scottish geographer
- Alexander Robert Johnston (1812âÂÂ1888), British colonial official
- Alexander Johnston (artist) (1816âÂÂ1891), Scottish painter
- Alexander Keith Johnston (1844âÂÂ1879), Scottish geographer
- Alexander Johnston (footballer) (1881âÂÂ1917), Scottish footballer
- Alexander Johnston (historian) (died 1889), American historian
- Alexander Johnston (Canadian politician) (1867âÂÂ1951), Canadian journalist, civil servant and politician
- Alexander Johnston (Ontario politician), Canadian politician, Ontario MPP
- Alexander Johnston (British Army officer) (1884âÂÂ1952), Hampshire cricketer and army officer
- Alexander Johnston (civil servant) (1905âÂÂ1994), Scottish civil servant
- Alexander W. Johnston (died 1932), Member of the Legislative Council of Samoa
- Alex Johnston (Australian rules footballer) (1881âÂÂ1965), Australian rules footballer
- Alex Johnston (rugby league) (born 1995), Australian professional rugby league footballer
See also