The oldest narrative source mentioning him briefly is Adam of Bremen's Gesta Hammaburgensis ecclesiae pontificum of circa 1070.

All the sagas agree that Olaf eventually came to Kievan Rus', specifically the court of Vladimir the Great of Kiev.

Snorri Sturluson claims in Olaf Tryggvson's saga that Olaf was born on an islet in Fjærlandsvatnet, where his mother Astrid Eiriksdottir, daughter of Eirik Bjodaskalle, was hiding from her husband's killers, led by Harald Greycloak, the son of Eirik Bloodaxe.

The journey was not successful: in the Baltic Sea they were captured by Estonian vikings, and the people aboard were either killed or taken as slaves.

Klerkon considered Thorolf too old to be useful as a slave and killed him, and then sold the two boys to a man named Klerk for a ram.

Sigurd then went to Reas and bought Olaf and Thorgils out from slavery, and took the boys with him to Novgorod to live under the protection of Vladimir.

Still according to Heimskringla, one day in the Novgorod marketplace Olaf encountered Klerkon, his enslaver and the murderer of his foster father.

A mob followed the young boy as he fled to his protector Queen Allogia, with the intent of killing him for his misdeed.

In 982 he was caught in a storm and made port in Wendland, where he met Queen Geira, a daughter of King Burizleif.

Holy Roman Emperor Otto II assembled a great army of Saxons, Franks, Frisians, and Wends to fight the Norse pagan Danes.

Otto's army was unable to break the fortification, so he changed tactics and sailed around it to Jutland with a large fleet.

[13] However, Henrietta Leyser, the author of Ælfheah's entry in the Oxford National Dictionary of Biography, states that Olaf was already baptized and that the 994 event at Andover was a confirmation of his faith, part of a Danegeld treaty in which he agreed to no longer raid in England.

This caught the ear of Jarl Haakon, who sent Thorer Klakka to Ireland, posing as a merchant, to see if he was the son of Tryggve Olafson.

Thorer befriended Olaf and told him of the situation in Norway, that Jarl Haakon had become unpopular with the populace, because he often took daughters of the elite as concubines, which was his right as ruler.

When he arrived many men had already revolted against Haakon, who was forced to hide in a hole dug in a pigsty, together with his slave, Kark.

He could not leave the pigsty, nor could he stay awake indefinitely, and when he fell asleep Kark decapitated Haakon with a knife.

It was a suitable site because the River Nid twisted itself before going into the fjord, creating a peninsula that could be easily defended against terrestrial attacks by only one short wall.

Both his Wendish and his Irish wife had brought Olaf wealth and good fortune, but, according to the Sagas, his last wife, Tyra, was his undoing, for it was on an expedition undertaken in 1000 to wrest her lands from Burislav that he was waylaid off the island Svolder by the combined Swedish, Danish, and Wendish fleets, together with the ships of Earl Haakon's sons.

[16] It has been suggested that Olaf's ambition was to rule a united Christian Scandinavia, and it is known that he made overtures of marriage to Sigrid the Haughty, queen of Sweden, but negotiations failed because of her steadfast pagan faith.

While Olaf sent missionaries to other lands and baptized dignitaries who visited Norway to spread Christianity, within his own kingdom he used forced conversion through means such as exile, hostage taking, mutilation, torture, and death for those who refused as well as destroying pagan temples.

[19][6] Noted victims include Thorlief the Wise who had one eye torn out—his torturers were supposed to blind him but his stoic bearing during the torture led them to run away after doing only half the job—and Raud the Strong who had a venomous snake forced into body through his mouth by a red hot iron.

[5] He died at the sea Battle of Svolder when his forces were defeated by a combined armada from Denmark, Sweden and the Jarls of Lade.

Finally surrounded on his flagship the Ormrinn Langi (Long Serpent), Danish sources report that when all was lost he committed suicide by throwing himself into the sea, "the end befitting his life", according to Adam of Bremen.

[20] Saxo Grammaticus says that Olaf preferred suicide to death at the hands of the enemy and jumped overboard in full armour rather than see his foes victorious.

It was seen that as the fighting lessened he stood, still alive, on the high-deck astern on the Long Serpent, which had thirty-two rowing places.

"[22]Other sagas suggest that one way or another Olaf made his way to the shore; perhaps by swimming, perhaps with the help of angels, most likely rescued by one of the Wendish ships present.

[24] In the early 11th century, a Viking chieftain named Tryggvi invaded Norway, claiming to be the son of Olaf and Gyda.

After questioning the purported killer and hearing him confess, King Harald had the man hanged, citing the familial bond between him and Tryggvi and his duty to avenge the latter's death.

Accounts reported by Oddr Snorrason included sightings of Olaf in Rome, Jerusalem, and elsewhere in Europe and the Mediterranean.