Sviatoslav or Svyatoslav I Igorevich (Old East Slavic: Свѧтославъ Игорєвичь, romanized: Svętoslavŭ Igorevičǐ;[1] Old Norse: Sveinald;[a] c. 943 – 972) was Prince of Kiev from 945 until his death in 972.

He conquered numerous East Slavic tribes, defeated the Alans and attacked the Volga Bulgars,[4][5] and at times was allied with the Pechenegs and Magyars (Hungarians).

[6][7][8][9] His decade-long reign over the Kievan Rus' was marked by rapid expansion into the Volga River valley, the Pontic steppe, and the Balkans, leading him to carve out for himself the largest state in Europe.

[19] The 10th-century Eastern Roman Emperor Constantine VII's Greek-language work De Administrando Imperio ("On the Governance of the Empire") records his name as Σφενδοσθλάβος ("Sfendostlabos").

[23] According to the Primary Chronicle, he carried neither wagons nor kettles on his expeditions, and he boiled no meat, rather cutting off small strips of horseflesh, game, or beef to eat after roasting it on the coals.

[30] By Malusha, a woman of indeterminate origins,[31] Sviatoslav had Vladimir, who would ultimately break with his father's paganism and convert Rus' to Christianity.

[32] Children Predslava Malusha Shortly after his accession to the throne, Sviatoslav began campaigning to expand Rus' control over the Volga valley and the Pontic steppe region.

"[40] The exact chronology of his Khazar campaign is uncertain and disputed; for example, Mikhail Artamonov and David Christian proposed that the sack of Sarkel came after the destruction of Atil.

[41] Although Ibn Haukal reports the sack of Samandar by Sviatoslav, the Rus' leader did not bother to occupy the Khazar heartlands north of the Caucasus Mountains permanently.

To the chagrin of his boyars and his mother (who died within three days after learning about his decision), Sviatoslav decided to move his capital to Pereyaslavets in the mouth of the Danube due to the great potential of that location as a commercial hub.

In the Primary Chronicle record for 969, Sviatoslav explains that it is to Pereyaslavets, the centre of his lands, that "all the riches flow: gold, silks, wine, and various fruits from Greece, silver and horses from Hungary and Bohemia, and from Rus' furs, wax, honey, and slaves".

At the head of an army that included Pecheneg and Magyar auxiliary troops, he invaded Bulgaria again, devastating Thrace, capturing the city of Philippopolis, and massacring its inhabitants.

Challenging Byzantine authority, Sviatoslav crossed the Danube and laid siege to Adrianople, causing panic in the streets of Constantinople in summer 970.

[53] Meanwhile, John, having quelled the revolt of Bardas Phokas, came to the Balkans with a large army and promoting himself as the liberator of Bulgaria from Sviatoslav, penetrated the impracticable mountain passes and shortly thereafter captured Marcianopolis, where the Rus' were holding a number of Bulgar princes hostage.

Cut off and surrounded, Sviatoslav came to terms with John and agreed to abandon the Balkans, renounce his claims to the southern Crimea, and return west of the Dnieper River.

[54] While Sviatoslav's campaign brought no tangible results for the Rus', it weakened the Bulgarian state and left it vulnerable to the attacks of Basil the Bulgar-Slayer four decades later.

[55] According to the Slavic chronicle, Sveneld attempted to warn Sviatoslav to avoid the Dnieper rapids, but the prince slighted his wise advice and was ambushed and slain by the Pechenegs when he tried to cross the cataracts near Khortytsia early in 972.

His figure first attracted attention of Russian artists and poets during the Russo-Turkish War (1768–1774), which provided obvious parallels with Sviatoslav's push towards Constantinople.

Russia's southward expansion and the imperialistic ventures of Catherine II in the Balkans seemed to have been legitimized by Sviatoslav's campaigns eight centuries earlier.

The Russian playwright chose to introduce Sviatoslav as his protagonist, although his active participation in the events following Igor's death is out of sync with the traditional chronology.

Написанное до войны)[59] as an epitome of militant Slavdom:[60] Знаменитый сок Дуная, Наливая в глубь главы, Стану пить я, вспоминая Светлых клич: "Иду на вы!".

Sviatoslav is the villain of the novel The Lost Kingdom, or the Passing of the Khazars, by Samuel Gordon,[61] a fictionalised account of the destruction of Khazaria by the Rus'.

[62] In 2005, reports circulated that a village in the Belgorod region had erected a monument to Sviatoslav's victory over the Khazars by the Russian sculptor Vyacheslav Klykov.

[63] The Press Centre of the Belgorod Regional Administration responded by stating that a planned monument to Sviatoslav had not yet been constructed but would show "respect towards representatives of all nationalities and religions.

Sviatoslav is the main character of the books Knyaz (Kniaz) and The Hero (Geroi), written by Russian writer Alexander Mazin.

In November 2011, a Ukrainian fisherman found a one metre long sword in the waters of the Dnieper on Khortytsia, near where Sviatoslav is believed to have been killed in 972.