Josef Bohuslav Foerster (30 December 1859 – 29 May 1951) was a Czech composer of classical music. He is often referred to as J. B. Foerster. The surname is sometimes spelled Förster.
Foerster was born in Prague. His ancestors were of Bohemian German ethnicity, but had assimilated into the Czech community. The family normally lived in Prague and was musical. His father, a composer also named Josef Foerster, taught at the Conservatory. (His father's students included Franz Lehár.) His brother was artist Viktor Foerster. Josef was educated accordingly, and duly studied there. He also showed an early interest in the theatre, and thought of becoming an actor. From 1884 he worked as a critic, and he would prove to be a writer of distinction. In 1893 he married the leading Czech soprano Berta Lautererová (Bertha Lauterer) in Hamburg, during ten years making his living there as a critic, and she was engaged at the Hamburg Staatsoper. In 1901 he became a teacher at the Hamburg Conservatory. In 1903 Berta went to sing at the Vienna Hofoper, and so Josef moved there with her, continuing to make a living as a music critic. He returned to Prague on the foundation of the Czechoslovak Republic in 1918, thereafter teaching at the conservatory and the university.
In 1946 he was declared a National Composer. He died in Nový Vestec.
Foerster produced numerous compositions. His music is not nationalistic in the sense of employing the idioms of Czech folk music. His work, words and music, is considered very subjective and personal, mystical and idealistic.
Foerster's opera Eva is another example, like Leoš Janáček's Jenůfa, of a libretto based on a play by Gabriela Preissová, though his treatment differs.