Onstad is a Norwegian surname. Notable people with the surname include:
Chris Onstad (born 1975), American writer, cartoonist, and artist Erik Gjems-Onstad (1922–2011), Norwegian resistance member, lawyer, and politician Kari Onstad (1941–2020), Norwegian singer and actress Katrina Onstad, Canadian journalist and novelist Kenton Onstad (born 1953), American politician, member of the North Dakota House of Representatives Kristian Flittie Onstad (born 1984), Norwegian professional football defender Mike Ohnstad (1926–2026), American politician in Minnesota Niels Onstad (1909–1978), Norwegian shipping executive Oda Utsi Onstad (born 1990), Norwegian long and triple jumper Ole Gjems-Onstad (born 1950), Norwegian jurist Otto Onstad (1874–1961), American politician Pat Onstad (born 1968), Canadian professional soccer goalkeeper
See also Onstad Township, Polk County, Minnesota, United States Henie Onstad Kunstsenter, art museum in Oslo, Norway