Harald Henrik Sager Kidde (14 August 1878 in Vejle – 23 November 1918 in Copenhagen) was a Danish writer and brother of the politician Aage Kidde. He is best known for the novel Helten (The Hero), which is one of the key novels in Danish literature. Kidde died of Spanish flu in 1918. He was only 40 years old at the time. There is an extensive Kidde-archive at Vejle Town Archive.