Lex van Delden, born Alexander Zwaap (10 September 1919–1 July 1988) was a Dutch composer.
Born Alexander Zwaap in Amsterdam (the Netherlands) as the only child of Wolf Zwaap, a school-teacher, and his wife Sara Olivier, Lex van Delden took piano-lessons from an early age - first from Martha Zwaga and later from the celebrated pianist, Cor de Groot. He started composing at the age of eleven, when he set poems by Guido Gezelle to music since a long illness prevented him from playing the piano. He remained self-taught as a composer. Despite his artistic promise and interests (by the age of fourteen, for instance, he was accompanying the famous German Expressionist dancer/choreographer, Gertrud Leistikow, and he also moved in the circle of one of Holland's foremost composers of the time, Sem Dresden) he enrolled at the University of Amsterdam in 1938 to study medicine.
Still a student, he made his début as a composer in 1940 with the song cycle L'amour (1939; for soprano, flute, clarinet and string trio), written at the request of the young composer/conductor Nico Richter, who was in charge of the students' orchestra.
However, in 1940 the Germans invaded the Netherlands and in 1942,