Jane Foster first appeared in Journey into Mystery #84 (September 1962), created by Stan Lee, Larry Lieber, and Jack Kirby. Initially introduced as a nurse working for Dr. Donald Blake, the mortal alter-ego of the Asgardian god Thor, she served as his colleague and eventual romantic interest. Over the early decades of Thor's publications, Jane remained a key supporting character, often entangled in Asgardian affairs while demonstrating resilience and compassion. Her role evolved gradually, transitioning from a damsel-like figure to a more independent professional, eventually becoming a physician and engaging in humanitarian and scientific pursuits that brought her back into Thor's orbit.
A transformative chapter in Jane Foster's history began in 2014, during Jason Aaron's run on Thor. Diagnosed with breast cancer and undergoing chemotherapy, Jane discovered Mjolnir after the original Thor, Odinson, was rendered unworthy and lost the ability to wield it. Proving herself worthy, she lifted the hammer, gaining the powers of the Goddess of Thunder and adopting the mantle of Thor—distinguished as the Mighty Thor. This empowerment came at a profound cost, as each transformation purged the chemotherapy from her system, exacerbating her illness while allowing her to perform extraordinary feats of heroism.
As the Mighty Thor, Jane joined the Avengers, represented Midgard in the Congress of Worlds, and confronted cosmic threats, including the Mangog during the events leading into the War of the Realms. Her tenure culminated in a heroic sacrifice to defeat the Mangog, resulting in her death; however, she was revived through the combined power of Odin and Odinson, with her cancer entering remission. Subsequently, Jane assumed the role of Valkyrie for a period, wielding the Undrjarn the All-Weapon, before returning to the mantle of Thor in later stories, solidifying her legacy as a multifaceted and enduring hero in the Marvel Universe.