Unui Doo (born Chan Yau-nui; c. 1874 – 18 August 1940) was a Chinese New Zealand businesswoman and shopkeeper. Born in Xinhui, Guangdong, she immigrated to New Zealand in 1915. She managed a grocery store in Auckland that served as a social centre for the Chinese community. Known as "Grandmother Doo", she was the matriarch of the Doo clan and one of the few Chinese women living in New Zealand before the 1930s.