Sadko (, the name of the main character) is an opera in seven scenes by Nikolai Rimsky-Korsakov. The libretto was written by the composer, with assistance from Vladimir Belsky, Vladimir Stasov, and others. Rimsky-Korsakov was first inspired by the Bylina of Sadko in 1867, when he completed a tone poem on the subject, his Op. 5. After finishing his second revision of this work in 1891, he decided to turn it into a dramatic work.