Gloag is a surname, and may refer to:
Ann Gloag (born 1942), Scottish businesswoman and charity campaigner Helen Gloag (1750–1790), of Perthshire, Scotland became the Empress of Morocco Helena Gloag (1909–1973), Scottish actress Isobel Lilian Gloag (1865–1917), English painter John Gloag (1896–1981), English novelist and nonfiction writer Joseph Gloag (ca. 1906–1977), Scottish marketing theorist and political activist Julian Gloag (born 1930), English novelist and screenwriter Paton James Gloag (1823–1906), Scottish minister and theological author Robin Gloag (1943–2007), co-founder of Stagecoach Group Thomas Gloag (born 2001), English cyclist William Gloag (lawyer) (1865–1934), Scottish lawyer and academic William Gloag, Lord Kincairney (1828–1909), Scottish judge