Kurse

While Kurse is originally one of Thor's Enemies he became one of the heroes and Thor's ally as well as one of the defenders of Asgard.

History
The being called Kurse was originally Algrim the Strong, one of the Dark Elves of the extradimensional realm of Svartalfheim who served the Dark Elves' ruler, Malekith the Accursed. Malekith captured Lorelei, an Asgardian woman who had used a magical potion to make the Asgardian thunder god Thor fall deeply in love with her. To rescue Lorelei, Thor went to the English Cotswolds, where stood the faerie castle that serves as a nexus between Earth and the other dimensional faerie realm of Svartalfheim. Thor broke through into the world of faerie, and seeing Lorelei menaced by Malekith, became oblivious to everything else. Hence, he was easily ambushed by the superhumanly strong Algrim, who stood in shadow wearing ebony armor. Malekith had told Algrim he had chosen him to defeat Thor. But while Thor and Algrim fought each other, Malekith ordered that a pitfall be opened beneath their feet. Thor and Algrim fell down a great chasm towards a lake of molten lava. Thor summoned his magic hammer Mjolnir, which carried him to safety, but Algrim plunged into the magma.

The magma's tremendous heat left Algrim on the brink of death. He would have been killed outright except that his enchanted armor protected him from the magma's full effects, and that his desire for vengeance on Thor gave him the will to live. In fact, the intense pain the magma caused him rendered Algrim amnesiac: not remembering the real reason why he fell into the lava, he knew only that Thor was somehow to blame.

Algrim's hatred of Thor was sensed by the incredibly powerful Beyonder who had come to Earth to investigate the nature of desire. Intrigued, the Beyonder decided, as an experiment, to restore Algrim to health, give him vastly greater strength and remodel his armor, and then see what Algrim would do. Somehow sensing that he would find Thor in New York City, Algrim, now transformed into the being called Kurse, passed from Svartalfheim to Earth and began walking across the ocean bottom to get to New York.

In New York City Kurse mistook Beta Ray Bill for Thor and attacked him. Bill escaped death at the far stronger Kurse's hands by reverting to his original, non-super-powered form, in which he no longer resembled Thor. Driven by insane hatred, Kurse wreaked havoc in Manhattan as he searched for Thor. In the process he severely injured Margaret Power, mother of the superhuman children known as Power Pack. Power Pack sought out Kurse and succeeded in burying him alive by causing the collapse of a building under construction. Mrs. Power has since recovered.

But Kurse succeeded in freeing himself that very same day, found Thor, and attacked him. Kurse was now stronger than Thor, so Thor donned his belt of strength, which doubled his strength. The observing Beyonder then vastly increased Kurse's strength so that it again greatly surpassed Thor's. Beta Ray Bill and Power Pack then arrived to join the battle. Thor used his hammer to project intensive heat at Kurse. The heat, reminding Kurse of the lava pit, reawakened his memories of how he came to fall into it. At last Kurse realized that it was not Thor but Malekith who was responsible, and his hatred therefore shifted from Thor to Malekith. On Thor's instructions, Energizer, a member of Power Pack, absorbed energy from both Thor's and Beta Ray Bill's enchanted hammers and then fired a tremendously powerful ball of energy at Kurse, which rendered him unconscious. Thor then suggested to the Beyonder that Kurse be transported to Hel, the realm ruled by the Asgardian death goddess Hela, to search for Malekith, who might be there. Thor was also hoping that Kurse would cause trouble for Hela while he was there.[1] The Beyonder agreed, and teleported Kurse to Hel.

Kurse wreaked havoc in Hel looking for Malekith, who was not there, and Hela had Kurse driven into Asgard itself. There Kurse finally found Malekith, who had used his shape-changing powers to become a double for the Asgardian Balder. Kurse slew Malekith, and then, his mission of vengeance finally fulfilled, he became peaceful and submissive. When last seen, Kurse was being taken by the Asgardian Heimdall to the latter's great hall.

Later, Kurse aided the true Balder in defending Asgard against the Frost Giants, and was re-christened Valgoth. Kurse now served as a protector of Asgard's children. He gave his life protecting them during Ragnarok.