Alnæs is a surname. Notable people with this surname include: Eyvind Alnæs (1872–1932), Norwegian composer, pianist, organist and choir director Finn Alnæs (1932–1991), Norwegian novelist Frode Alnæs (born 1959), Norwegian jazz guitarist and composer Ivar Alnæs (1868–1956), Norwegian teacher and linguist Karsten Alnæs (born 1938), Norwegian author, historian, and journalist Kirsten Alnæs (1927–2021), Norwegian social anthropologist