Sergei Sergeyevich Prokofiev (27 April [O.S. 15 April] 1891 – 5 March 1953) was a Russian composer, pianist, and conductor who later worked in the Soviet Union. As the creator of acknowledged masterpieces across numerous music genres, he is regarded as one of the major composers of the 20th century. His works include such widely heard pieces as the March from The Love for Three Oranges, the suite Lieutenant Kijé, the ballet Romeo and Juliet—from which "Dance of the Knights" is taken—and Peter and the Wolf. Of the established forms and genres in which he worked, he created—excluding juvenilia—seven completed operas, seven symphonies, eight ballets, five piano concertos, two violin concertos, a cello concerto, a symphony-concerto for cello and orchestra, and nine completed piano sonatas.

A graduate of the Saint Petersburg Conservatory, Prokofiev initially made his name as an iconoclastic composer-pianist, achieving notoriety with a series of ferociously dissonant and virtuosic works for his instrument, including his first two piano concertos. In 1915, Prokofiev made a decisive break from the standard composer-pianist category with his orchestral Scythian Suite, compiled from music originally composed for a ballet commissioned by Sergei Diaghilev of the Ballets Russes. Diaghilev commissioned three further ballets from Prokofiev—Chout, Le pas d'acier and The Prodigal Son—which, at the time of their original production, all caused a sensation among both critics and colleagues. But Prokofiev's greatest interest was opera, and he composed several works in that genre, including The Gambler and The Fiery Angel. Prokofiev's one operatic success during his lifetime was The Love for Three Oranges, composed for the Chicago Opera and performed over the following decade in Europe and Russia.

After the Revolution of 1917, Prokofiev left Russia with the approval of Soviet People's Commissar Anatoly Lunacharsky, and resided in the United States, then Germany, then Paris, making his living as a composer, pianist and conductor. In 1923 he married a Spanish singer, Carolina (Lina) Codina, with whom he had two sons; they divorced in 1947. In the early 1930s, the Great Depression diminished opportunities for Prokofiev's ballets and operas to be staged in America and Western Europe. Prokofiev, who regarded himself as a composer foremost, resented the time taken by touring as a pianist, and increasingly turned to the Soviet Union for commissions of new music; in 1936, he finally returned to his homeland with his family. His greatest Soviet successes included Lieutenant Kijé, Peter and the Wolf, Romeo and Juliet, Cinderella, Alexander Nevsky, the Fifth and Sixth Symphonies, On Guard for Peace, and the Piano Sonatas Nos. 6–8.

The Nazi invasion of the USSR spurred Prokofiev to compose his most ambitious work, an operatic version of Leo Tolstoy's War and Peace; he co-wrote the libretto with Mira Mendelson, his longtime companion and later second wife. In 1948, Prokofiev was attacked for producing "anti-democratic formalism". Nevertheless, he enjoyed personal and artistic support from a new generation of Russian performers, notably Sviatoslav Richter and Mstislav Rostropovich: he wrote his Ninth Piano Sonata for the former and his Symphony-Concerto for the latter.

Prokofiev was born in 1891 in a rural estate in Sontsovka, Bakhmut uezd, Yekaterinoslav Governorate, Russian Empire (now known as Sontsivka, Pokrovsk Raion, Donetsk Oblast, Ukraine). His father, Sergei Alekseyevich Prokofiev, was an agronomist from a mercantile family in Moscow. Prokofiev's mother, Maria (née Zhitkova), came from a Saint Petersburg family of former serfs who had been owned by the Sheremetev family, under whose patronage serf-children were taught theatre and arts from an early age. She was described by Reinhold Glière, Prokofiev's first composition teacher, as "a tall woman with beautiful, clever eyes … who knew how to create an atmosphere of warmth and simplicity about her." After their wedding in the summer of 1877, the Prokofievs moved to a small estate in the Smolensk governorate. Eventually, Sergei Alekseyevich found employment as a soil engineer, employed by one of his former fellow-students, Dmitri Sontsov, to whose estate in the Ukrainian steppes the Prokofievs moved.

By the time of Prokofiev's birth, Maria—having previously lost two daughters—had devoted her life to music; during her son's early childhood, she spent two months a year in Moscow or St Petersburg taking piano lessons. Sergei Prokofiev was inspired by hearing his mother practicing the piano in the evenings, mostly works by Chopin and Beethoven, and wrote his first piano composition at the age of five, an "Indian Gallop", which was written down by his mother: it was in the F Lydian mode (a major scale with a raised 4th scale degree), as the young Prokofiev felt "reluctance to tackle the black notes". By seven, he had also learned to play chess. Chess remained a passion of his, and he became acquainted with world chess champions José Raúl Capablanca, whom he beat in a simultaneous exhibition match in 1914, and Mikhail Botvinnik, with whom he played several matches in the 1930s. At the age of nine, he composed his first opera, The Giant, as well as an overture and various other pieces. Opera remained thereafter as the genre Prokofiev was most fond of working in.

In 1902, Prokofiev's mother met Sergei Taneyev, director of the Moscow Conservatory, who initially suggested that Prokofiev should start lessons in piano and composition with Alexander Goldenweiser. Unable to arrange that, Taneyev instead arranged for composer and pianist Reinhold Glière to spend the summer of 1902 in Sontsovka teaching Prokofiev. The first series of lessons culminated, at the 11-year-old Prokofiev's insistence, with the budding composer making his first attempt to write a symphony. The following summer, Glière revisited Sontsovka to give further tuition. When, decades later, Prokofiev wrote about his lessons with Glière, he gave due credit to his teacher's sympathetic method but complained that Glière had introduced him to "square" phrase structure and conventional modulations, which he subsequently had to unlearn. Nonetheless, equipped with the necessary theoretical tools, Prokofiev started experimenting with dissonant harmonies and unusual time signatures in a series of short piano pieces he called "ditties" (after the so-called "song form", more accurately ternary form, on which they were based), laying the basis for his own musical style.

Despite his growing talent, Prokofiev's parents hesitated over starting their son on a musical career at such an early age, and considered the possibility of his attending a good high school in Moscow. By 1904, his mother had decided instead on Saint Petersburg, and she and Prokofiev visited the then capital to explore the possibility of moving there for his education. They were introduced to composer Alexander Glazunov, a professor at the Saint Petersburg Conservatory, who asked to see Prokofiev and his music; Prokofiev had composed two more operas, Desert Islands and The Feast during the Plague, and was working on his fourth, Undina. Glazunov was so impressed that he urged Prokofiev's mother to have her son apply for admission to the Conservatory. He passed the introductory tests and enrolled that year.