Sergei Vasilievich Rachmaninoff (1 April 1873 – 28 March 1943) was a Russian-born composer, pianist, and conductor. Rachmaninoff is widely considered one of the finest pianists of his day and, as a composer, one of the last great representatives of Romanticism in Russian classical music.
Early influences of Tchaikovsky, Rimsky-Korsakov, and other Russian composers gave way to a personal style notable for its song-like melodicism, expressiveness and his use of rich orchestral colors. The piano is featured prominently in Rachmaninoff's compositional output, and through his own skills as a performer he explored the expressive possibilities of the instrument.

Liturgy of St John Chrysostom, Op. 31, is a musical work by Sergei Rachmaninoff, one of his two major unaccompanied choral works (the other being his All-Night Vigil). The Divine Liturgy of St. John Chrysostom is the primary worship service of the Eastern Orthodox Church.