Geirröðr

In Norse mythology, Geirröd was a jötunn and the father of the giantesses Gjálp and Greip.

The story of Geirröd is told in Þórsdrápa. Loki, while flying as a hawk, was captured by Geirröd. Because he hated Thor, Geirröd demanded that Loki bring his enemy to Geirröd's castle without his magic belt and hammer. Loki agreed to lead Thor to the trap. On the way to Geirröd's castle, Loki and Thor stopped at the home of Grid, a giantess. She waited until Loki left the room, then told Thor what was happening and gave him her iron gloves and magical belt and staff. Thor killed Geirröd, followed by all other giants he could find, including Geirrod's daughters, Gjalp and Greip.

...
Wikipedia