Lehmer is a surname. Notable people with the surname include:
Derrick Norman Lehmer (1867–1938), number theorist who produced tables of prime factors and mechanical devices like Lehmer sieves
Derrick Henry Lehmer (1905–1991), number theorist known for Lucas–Lehmer test, son of D. N. Lehmer and husband of Emma Lehmer
Emma Lehmer (1906–2007), Russian methematician, known for her work on reciprocity laws, wife of D. H. Lehmer
Kat Lehmer, American film director, writer, actor and artist