Mykola Dmytrovych Leontovych (13 December [O.S. 1 December] 1877 – 23 January 1921; Ukrainian: Микола Дмитрович Леонтович (listen); also Leontovich) was a Ukrainian composer, conductor, ethnomusicologist and teacher. His music was inspired by the Ukrainian composer Mykola Lysenko and the Ukrainian National Music School. Leontovych specialised in a cappella choral music, ranging from original compositions, to church music, to elaborate arrangements of folk music.

Leontovych was born and raised in the Podolia province of the Russian Empire (now in Ukraine). He was educated as a priest in the Kamianets-Podilskyi Theological Seminary and later furthered his musical education at the Saint Petersburg Court Capella, and by means of private lessons with Boleslav Yavorsky. With the independence of the Ukrainian state in the 1917 revolution, Leontovych moved to Kyiv, where he worked at the Kyiv Conservatory and the Mykola Lysenko Institute of Music and Drama. He composed "Shchedryk" in 1904 (premiered in 1916), now known to the English-speaking world as "Carol of the Bells". He was murdered by a Soviet agent in 1921, and is known as a martyr in the Eastern Orthodox Ukrainian Church, where he is also remembered for his liturgy, the first liturgy composed in the vernacular, specifically in the modern Ukrainian language.

During his lifetime, Leontovych's compositions and arrangements became popular with musicians across the Ukrainian region of the Russian Empire. Performances of his works in western Europe and North America earned him the nickname "the Ukrainian Bach". Apart from "Shchedryk", Leontovych's music is performed primarily in Ukraine and by the Ukrainian diaspora.