Zdeněk Fibich (full name Zdeněk Antonín Václav Fibich; 21 December 1850 – 15 October 1900) was a Czech composer. Also known as Zdenik or Zdenko, he supported the development of an independent Czech musical culture alongside Bedřich Smetana and Antonín Dvořák.
Fibich was born in Všebořice, near Kutná Hora, the son of a forester. His mother, who recognized his musical ability, gave him his first lessons and encouraged him to study music. At fourteen he conducted a symphony of his own composition, and a year later he began writing an opera. He studied at the Felix Mendelssohn College of Music and Theatre in 1865–1866, as well as in Vienna, Prague with Smetana, Leipzig, Paris and Mannheim.
He worked as a conductor in Poland and Vilnius before returning to Prague in 1874 to concentrate on composition. From 1875 to 1878 he served as second Kapellmeister at the Provisional Theatre, and from 1878 to 1880 he directed the choir of Prague's Russian Church. In 1899 he became opera dramaturge at the National Theatre in Prague. He also worked as a music teacher; his pupils included Karel Kovařovic, Franz Lehár, Zdeněk Nejedlý and Otakar Ostrčil.
Fibich wrote more than 600 works, including operas, three symphonies, overtures, symphonic poems, chamber music, songs, duets, melodramas and about 350 piano pieces. His seven operas show, in part, the influence of Richard Wagner. His stage works include the Hippodamia trilogy, with texts by Jaroslav Vrchlický, and his best-known work is the piano piece Poem, later arranged for violin and for orchestra. Other orchestral works include the Symphony No. 1 in F major, At Twilight, Othello, the Comenius Overture, and Toman and the Wood Nymph.
Fibich died in Prague and was buried at Vyšehrad.