Alexandr Dmitriyevich Kastal'sky (1856–1921) was a prominent Russian composer and conductor, best known for his contributions to choral music and liturgical works. He was a significant figure in the Russian choral tradition, particularly noted for his role in the development of Russian Orthodox music. Kastal'sky's music often incorporates folk elements and rich harmonies, reflecting the spiritual and cultural heritage of Russia. One of his notable works is the "Vespers" (also known as "All-Night Vigil"), which showcases his mastery of choral writing and his ability to blend traditional Russian liturgical music with contemporary harmonies of his time. Additionally, his compositions for the Russian Orthodox Church, including various settings of the Divine Liturgy, have been influential in the revival of sacred choral music in Russia. Kastal's impact on music extends beyond his compositions; he was also a teacher and mentor to many young musicians, helping to shape the next generation of Russian composers. His dedication to preserving and promoting Russian choral traditions has left a lasting legacy in both sacred and secular music contexts.