Knudåge Riisager (6 March 1897 in Kunda, Estonia – 26 December 1974 in Copenhagen, Denmark[1]) was a Danish composer.
Knudåge Riisager was born in Estonia of Danish parents. His father Emil Riisager was an engineer, and the family returned to Denmark in 1900 when Knudåge was three years old.

He graduated from Copenhagen University where he received violin lessons from Peder Møller, and studied music theory under Otto Malling and Peder Gram. For many years he worked in a government job, and also as a composer. In 1923 he went to Paris to study with Albert Roussel and Paul Le Flem, where he experienced at first hand French neoclassicism and the music of Igor Stravinsky and Les Six.[2] Later he also studied in Leipzig with Hermann Grabner.
Knudåge Riisager's international fame is largely due to his extensive work in ballet music, which was primarily a result of collaboration with Harald Lander. The first work he composed for the Royal Danish Theatre was music for the ballet Benzin by Storm P. staged by Elna Ørnberg in 1930.

Knudåge Riisager was also an industrious writer: his bibliography includes nearly 400 titles spread over six decades. In 1956–67 he was director of the Royal Danish Academy of Music. His compositions are stored in the Music and Theatre Department at the Royal Danish Library.

He was a commander of the 1st degree in the Dannebrogordenen, and is buried at Tibirkegård.