DeMars (and variants) is a surname. Notable people with the surname include:
AnnMaria De Mars (born 1958), American technology executive, author and Judoka Billy DeMars (1925–2020), American baseball shortstop and coach Bruce DeMars, United States Navy four star admiral Hélène-Louise Demars (c. 1736–1778), French composer Jean-Odéo Demars (1695–1756), French organist and harpsichordist Lina van de Mars (born 1979), German TV moderator Nicole Demars (born 1970), Canadian road cyclist Vernon DeMars (1908–2005), American architect and professor
See also DeMar