Blackmar is a surname. Notable people with the surname include:
Armand Blackmar (1826–1888), American music publisher Charles Blakey Blackmar (1922–2007), American judge Elizabeth Blackmar, American historian, author, and professor Esbon Blackmar (1805–1857), American politician Frank W. Blackmar (1854–1931), American sociologist, historian and educator Phil Blackmar (born 1957), American golfer Wilmon W. Blackmar (1841–1905), Union Army officer and Medal of Honor recipient