Gigans were giant creatures, larger even than the giant from Jack and the Beanstalk or any giants from Nonestica. So large were they, that they could reshape entire landscapes for fun as if playing in the sand.

Forty gigans accompanied Nelebel on her exile from the Forest of Burzee, along with forty Ryls and forty Knooks. While the Fairy wept at her punishment, the Gigans rearranged the landscape on the Pacific coast where they had settled as a way to amuse themselves, creating the San Bernardino range of mountains, a great bay, and all the other geography of Coronado, California.

Later, Queen Lulea became annoyed at the awkwardness of the huge gigans and transformed them all into Rampsies, so there are no gigans at all in these days. ("Nelebel's Fairyland")