Othar Holmboe was a Norwegian pharmacist, illustrator and painter who grew up in Tromsø, where he trained as a pharmacist (1887) and helped establish Tromsø Kunstforening with his father, Othar Ervigius. Later, like his brother Thorolf Holmboe, he became a student at the Drawing School in Kristiania with study trips to Paris (1896) and Copenhagen (1900), and made his debut at the Autumn Exhibition (1898).

He had a wide range of interests, including illustrating Gabriel Scott's The Mysteries of Lillehavn (1898), decorating the altarpiece in Såner church, and publishing the biography Foged Jens Holmboe's descendants, Bogtrykkeriet Concordia (1890). Holmboe also designed poster series such as NSB's Norway - Land of the Midnight Sun (1905) and Mustad's margarine (1905). He eventually settled in Son, where he ran a pharmacy and served as mayor. He is biographed in the catalog Thorolf og Othar Holmboe, Nordnorsk Kunstmuseum (1996).