Keir is a surname and given name shortened from Keiron. Notable people with the name include:

• Andrew Keir (1926–1997), Scottish actor
• Colin Keir (born 1959), Scottish politician
• David Keir (1884–1971), British actor
• David Lindsay Keir (1895–1973), British historian
• Jack Keir (born 1957 or 1958), Canadian politician
• James Keir (1735–1820), Scottish scientist
• John Keir (1856–1937), British Army officer
• Leitch Keir (1861–1922), Scottish footballer
• Mary Keir (1912–2024), Welsh supercentenarian
• Nick Keir (1953–2013), Scottish musician

• Keir Clark (1910–2010), Canadian politician
• Keir Dillon (born 1977), American snowboarder
• Keir Dullea (born 1936), American actor
• Keir Gilchrist (born 1992), Canadian actor
• Keir Giles (born 1968), British writer
• Keir Graff (born 1969), American writer
• Keir Hardie (1856–1915), Scottish socialist, first leader of the UK Labour Party
• Keir Mather (born 1998), British politician
• Keir Nuttall (born 1975), Australian musician
• Keir O'Donnell (born 1978), Australian actor
• Keir Pearson (born 1966), American screenwriter
• Keir Simmons (born 1972), British journalist
• Keir Starmer (born 1962), Prime Minister of the United Kingdom
• Keir Thomas (born 1998), American football player