Demets, DeMets, or De Mets is a surname. Notable people with the surname include:
David DeMets (born 1944), American biostatistician Eugène Demets (1858–1923), French music publisher Fernand Demets (1884–1952), Belgian politician Gertjan De Mets (born 1987), Belgian footballer Stéphane Demets (born 1976), Belgian footballer