Hela is the daughter of Odin meaning she is the sister of Thor and Loki. Hela was first introduced in 'Thor Ragnarok', as herself, played by Cate Blanchett. Before Thor was born Hela and her father, Odin were fighting in battles together, as partners. But, Hela became extremely violent causing Odin to lock her underground until he died. Odin died and she was finally free, Thor found out that his hammer Mjölnir once belonged to Hela, but since she was locked Odin gave it to him. Hela destroyed the hammer and attempted to rule and destroy Asgard. Thor and Loki had to stop her, so they had to get help from the Valkyries. All the Valkyries died accept one, so they had to get help from the Valkyrie.