Harmer is a surname. Notable people with the surname include:
Alfred C. Harmer (1825–1900), US Congressman from PennsylvaniaAmbrose Harmer (died c.1647), Virginia colonial politicianBarbara Harmer (born 1954), English airline pilotDani Harmer (born 1989), British actressFlorence Harmer (1890–1976), English historianJohn Harmer (mayor) (fl. 1737–47), Virginia colonial politicianJohn L. Harmer (born c.1934), American politicianJuliet Harmer (born 1943), British actressNick Harmer (born 1975), American rock musicianSarah Harmer (born 1970), Canadian singer-songwriterWendy Harmer (born 1955), Australian writer & comedianSidney Frederic Harmer (1862–1950), British ZoologistRussell Harmer (1896–1940), British Olympic Gold Medallist