Alexander Keith may refer to:

• Alexander Keith (politician) (1795–1873), Canadian politician, freemason and brewer
• Alexander Keith (minister) (1791–1880), Scottish clergyman
• Alexander Keith, Jr. (1827–1875), Canadian mass murderer
• Sandy Keith (Alexander M. Keith, 1928–2020), American politician
• Alexander Keith, 18th-century Church of England clergyman responsible for thousands of clandestine marriages; see Keith's Chapel
• Sir Alexander Keith of Dunnottar, Knight Marischal (died 1819), namesake of the Keith Medal

• Alexander Keith's Brewery, brewery and beer brand
• Keith Alexander (disambiguation)