Marvel’s superheroine Sif is an Asgardian warrior with superstrength, speed, agility, and reflexes, she is a skilled fighter, heals very quickly, and can teleport. Based on the Norse goddess of the same name, Sif was created by Stan Lee and Jack Kirby and made her first appearance in Journey Into Mystery #102 (March 1964).

Sif is Heimdall’s sister (originally Balder’s sister) and has been one of Thor’s friends since childhood and later a love interest. When she was still a kid, Sif showed great potential to become a warrior on par with the best female warriors on Asgard.

Sif fought by Thor’s side after he returned from being banished on Earth, taking on Mangog, the Enchanters Three, Wrecker, Ulik, and others. She was a part of the group that resisted Loki when he wrested control of Asgard, putting herself on the line to keep him from murdering people.

At this point, Sif and Thor had rekindled their relationship, but she learned that he still had feelings for Jane Foster when she found him in her hospital room after she had been gravely injured. Though she was saddened and didn’t understand Thor’s attraction to the mortal, Sif shared her life force with Jane to save the human. Not long after that, their connection was severed, and Jane became trapped in a pocket dimension. Sif and Thor traversed the territory and save Jane.

When Thor became the king of Asgard, he tried to keep his home and Earth safe, but his well intentioned plans led to disastrous results. Because Thor became a tyrannical leader, Sif refused to fall in line and was banished from Asgard. Later Thor and Enchantress had a son, Magni, who found Sif during his travels. She convinced him to fight against his father’s disastrous reign, and he died during the conflict. Once Thor realized the mistakes he’d made, he used time travel to go back and undo what he had done.

After the timeline was reset, Loki brought about Ragnarök, and Sif lost an arm during the first battle. She was saved by Brunnhilde, who was then killed by Durok the Demolisher. To honor Brunnhilde, Sif took up her sword and led the Valkyrior during the final battle and died as Asgard fell.