Brundibár is a children's opera by Jewish-Czech composer Hans Krása with a libretto by Adolf Hoffmeister, originally performed by the children of Theresienstadt concentration camp in occupied Czechoslovakia. The name comes from a Czech colloquialism for a bumblebee.
Krása and Hoffmeister wrote the opera in 1938 for a government competition, but the competition was later cancelled due to political developments. Rehearsals started in 1941 at the Jewish orphanage in Prague. In the winter of 1942 the opera was first performed at the orphanage: by this time, composer Krása and set designer František Zelenka had already been transported to Theresienstadt. By July 1943, nearly all of the children of the original chorus and the orphanage staff had also been transported to Theresienstadt. Only the librettist Hoffmeister was able to escape Prague in time.
Reunited with the cast in Theresienstadt, Krása reconstructed the full score of the opera, based on memory and the partial piano score that remained in his hands, adapting it to suit the musical instruments available in the camp. On 23 September 1943, Brundibár premiered in Theresienstadt.