Hadingus was one of the earliest legendary Danish kings

Legendary Danish kings

The legendary kings of Denmark are the predecessors of Gorm the Old, half history and half legend. The accounts of the Danish kings are confusing and contradictory, and so this presentation tries to separate the various sources from each other...

 according to Saxo Grammaticus

Saxo Grammaticus

Saxo Grammaticus also known as Saxo cognomine Longus was a Danish historian, thought to have been a secular clerk or secretary to Absalon, Archbishop of Lund, foremost advisor to Valdemar I of Denmark. He is the author of the first full history of Denmark.- Life :The Jutland Chronicle gives...

' Gesta Danorum

Gesta Danorum

Gesta Danorum is a patriotic work of Danish history, by the 12th century author Saxo Grammaticus . It is the most ambitious literary undertaking of medieval Denmark and is an essential source for the nation's early history...

where he has a detailed biography. Georges Dumézil

Georges Dumézil

Georges Dumézil was a French comparative philologist best known for his analysis of sovereignty and power in Proto-Indo-European religion and society...

 and others have argued that Gram was partially modelled on the god Njörðr.

Gesta Danorum

Hadingus is the son of Gram and Signe, the daughter of Finnish King Sumble. Gram steals Signe from her wedding, kills the husband (Henry, King of Saxony) and takes her to Denmark, where Hadingus is born. When Gram is killed by Swipdag, King of Norway, Hadingus is taken to Sweden and is fostered by the giant Wagnofthus and his daughter Harthgrepa

Harthgrepa

Harthgrepa or Harðgreip in Old Norse is a giantess who appears in the legend of the Norse hero Hadingus, which is reported by Saxo Grammaticus in his Gesta Danorum.- Nursemaid, lover and companion of Hadingus:...

. He is eager to become a warrior but Harthgrepa tries to dissuade him from it in favor of entering into a quasi-incestuous love-relationship with herself.

Why doth thy life thus waste and wander? Why dost thou pass thy years unwed, following arms, thirsting for throats? Nor does my beauty draw thy vows. Carried away by excess of frenzy, thou art little prone to love. Steeped in blood and slaughter, thou judgest wars better than the bed, nor refreshest thy soul with incitements. Thy fierceness finds no leisure; dalliance is far from thee, and savagery fostered. Nor is thy hand free from blasphemy while thou loathest the rites of love. Let this hateful strictness pass away, let that loving warmth approach, and plight the troth of love to me, who gave thee the first breasts of milk in childhood, and helped thee, playing a mother's part, duteous to thy needs. The Danish History, Book One

Hadingus accepts Harthgrepa's embraces and when he wants to travel back to Denmark she accompanies him. After raising a man from the dead to obtain information, Harthgrepa is killed by supernatural beings. At this point Hadingus acquires a new patron, Odin

Odin

Odin is a major god in Norse mythology and the ruler of Asgard. Homologous with the Anglo-Saxon "Wōden" and the Old High German "Wotan", the name is descended from Proto-Germanic "*Wodanaz" or "*Wōđanaz"....

, who predicts his future and gives him advice.
Hadingus wages wars in the Baltic

Baltic countries

The term Baltic states refers to the Baltic territories which gained independence from the Russian Empire in the wake of World War I: primarily the contiguous trio of Estonia, Latvia, Lithuania ; Finland also fell within the scope of the term after initially gaining independence in the 1920s.The...

 and achieves victory and renown. He then returns to Scandinavia, defeats Suibdagerus, his father's slayer, and becomes king of Denmark. As king he has an eventful career ahead of him. He wars with Norwegians and Swedes, offends a god by killing a divine animal and atones for it by a sacrifice

Blót

The blót was Norse pagan sacrifice to the Norse gods and the spirits of the land. The sacrifice often took the form of a sacramental meal or feast. Related religious practices were performed by other Germanic peoples, such as the pagan Anglo-Saxons...

 to Freyr

Freyr

Freyr is one of the most important gods of Norse paganism. Freyr was highly associated with farming, weather and, as a phallic fertility god, Freyr "bestows peace and pleasure on mortals"...

, he rescues the princess Regnilda from giants and takes her as a wife, visits the underworld, participates in more wars and dies by hanging himself in front of his subjects.

The story of Hadding is retold in fictionalized form by Poul Anderson

Poul Anderson

Poul William Anderson was an American science fiction author who began his career during one of the Golden Ages of the genre and continued to write and remain popular into the 21st century. Anderson also authored several works of fantasy, historical novels, and a prodigious number of short stories...

in the novel War of the Gods.