Clas is a masculine given name. Notable people with the name include:
Clas Alströmer (1736–1794), Swedish naturalist Clas Bjerkander (1735–1795), Swedish meteorologist, botanist and entomologist Clas or Klaus Fleming (1535–1597), Finnish-born Swedish nobleman and admiral, Lord High Admiral and Lord High Constable Clas Larsson Fleming (1592–1644), an admiral and administrator of the Royal Swedish Navy Clas Frietzcky (1727–1803), Swedish politician Clas Lindberg (born 1956), Swedish film director and screenwriter Clas Theodor Odhner (1836–1904), Swedish historian and director of the Swedish National Archives Clas Thunberg (1893–1973), Finnish speed skater and five time Olympic gold medalist Clas Åkesson Tott (1590), Swedish field marshal and member of the Privy Council of Sweden Clas Åkesson Tott the Younger (1630–1674), Field marshal, Governor-General of Swedish Livonia and Ambassador in France
See also Claes