Mertz is a surname. Notable people with the surname include:
Albert Mertz (1920–1990), Danish painter
Albrecht Mertz von Quirnheim, (1905–1944), German officer and resistance fighter involved in the 20 July Plot against Adolf Hitler
Barbara Mertz (1927–2013), author of mystery and suspense novels who writes under the pseudonyms Elizabeth Peters and Barbara Michaels
Dolores Mertz (born 1928), Iowan politician
Ellen Louise Mertz (1896—1987), Danish geologist
Elizabeth Mertz, American linguistic and legal anthropologist
Harold Mertz, designer of the standard crash test dummy
Johann Kaspar Mertz (1806–1856), Austrian guitarist and composer
Lawrence Mertz, optical physicist and inventor of the Mertz corrector
LuEsther Mertz (1905–1991), founder of Publisher's Clearinghouse
Stephen Mertz (born 1947), American fiction author of thrillers and novels of suspense
Xavier Mertz (1883–1913), Swiss Antarctic explorer
Fictional characters:
Fred and Ethel Mertz, fictional couple on I Love Lucy