Karel Boleslav Jirák (né Karel Bohuslav Jirák; January 28, 1891, Prague, Bohemia – January 30, 1972, Chicago, Illinois, U.S.) was a Czechoslovak composer and conductor.

Jirák became a pupil of Josef Bohuslav Foerster and Vítězslav Novák at the Charles University and at music academy in Prague.

From 1915-18 he was the Kapellmeister at the Hamburg Opera and worked from 1918 to 1919 as a conductor at the National Theatre in Brno and Ostrava.

[1] From 1920-30, he was a composition teacher at the Prague Conservatory, and principal conductor of the Czechoslovak Radio Orchestra until 1945.

[1] Jirák's opera was Apolonius z Tyany (Apollonius of Tyana, 1912–1913), which was initially ignored by Prague's National Theatre and later accepted under the title Žena a Bůh (The Woman and the God, 1936).