Gjalp is a giantess, the daughter of the Jotunn Geirrod, and the sister of Greip.
Magnus Chase and the Gods of Asgard
The Sword of Summer
Magnus and Samirah first encounter Gjalp and her sister Griep in Geirrod's palace, where they went to retrieve Thor's hammer Mjolnir. Magnus and Sam quickly claim guest rights to prevent the two giantesses from killing them directly, although the daughters of Geirrod still attempt to kill them in more subtle ways, such as trying to raise the chair Magnus and Sam are seated on onto the ceiling so that they will get crushed to death. Afterwards, the twin giantesses try to barter for Jack in exchange for Thor's Staff. Magnus refuses and throws Jack into Griep and Gjalp's nasal cavities which scrambles their brains and kills them altogether.