Greip is a Jotunn, daughter of the Jotunn, Geirrod, and sister of Gjalp.

Magnus Chase and the Gods of Asgard

The Sword of Summer

Magnus and Sam go to her father's palace to find Mjølnir. The demigods claim guest rights so they well not be killed. Greip and Gjalp are killed by Magnus and Jack when they fail to make an agreement.