Thor: Ragnarok introduced a ton of exciting new characters into the Marvel Cinematic Universe, such as Tessa Thompson's boozy but vicious Valkyrie, Taika Waititi's comic relief Korg, and Jeff Goldblum's very Jeff Goldblum-y Grandmaster. But the most menacing of all is Hela, the powerful goddess of death set on taking over Asgard. Cate Blanchett's scary new villain explains a good chunk of her backstory, but fans may still be asking who is Hela's mother. And hardcore fans are probably wondering whether the Marvel movies will follow the same crazy genealogy as the source comic books, because if they do, then moviegoers are in for a huge shock if Hela's true parentage is revealed. Spoiler alert: Obviously, don't read on if you haven't seen Thor: Ragnarok yet.
Shortly after Thor: Ragnarok begins, Thor and Loki meet Hela, who was freed from her imprisonment after Odin peacefully died on a cliffside in Norway. Hela explains that she is Odin's firstborn daughter, and that their father banished her after her ambitions for power grew too strong. Later in the movie, we discover that Hela crusaded alongside Odin in ancient times as they both conquered planets and built up Asgard as an intergalactic superpower, but when Odin decided to end his crusades and foster peace in Asgard, Hela disagreed and was sent away.
So, the movie seems to be making it pretty clear that Odin is Hela's father, but what about her mother? That part is still a mystery. If Asgard's former queen Frigga is indeed Hela's mother, then she is Thor's full sister, but this is never clarified. Due to the mystery, fans are expected something pretty shocking could be revealed about Hela's genealogy in the upcoming movies.
If Odin really is Hela's father in the movies, then it is actually a major change from the Marvel comic books. That's because Hela's father in the comics is — wait for it — Loki! I know, weird, right? In the books, Loki and a giantess named Angrboða give birth to Hela, and she is appointed the goddess of death by Odin when she comes of age. Obviously, it seems like the Marvel Cinematic Universe chose to rework the character's parentage, since Thor: Ragnarok introduces Hela as an older sister to Thor and Loki. But fans think that the comic book genealogy may still influence a bit of a twist in the Marvel movies.
Since we only know who Loki's father is at this point (the Frost Giant Laufey) and the movies have yet to reveal the identity of his mother, there are a bunch of theories popping up that the movies may flip the comic-book relationship between Hela and Loki and actually reveal Hela to be Loki's mother. Reddit theories that the MCU would make Hela Loki's mother began growing a year ago after Cate Blanchett's casting as the character was announced, and have continued to make the rounds with more gusto recently. If this theory played out to be true, then it would actually make Thor Loki's uncle, and Odin Loki's biological grandfather. It would also be the source of a ton of drama between the Asgardian royal family, of course.
But all this speculation may wind up being for nothing, since it appears that Hela is destroyed along with Asgard at the end of Thor: Ragnarok. Though it is assumed that Hela died in the planetary explosion, we know that she's definitely not an easy person to kill and could very well have found some way to survive. We will just have to wait and see if she returns in next year's Avengers: Infinity War and whether the movie will explore her relationship to Loki or not.