Sköll and Hati

Sköll and Hati are the wolves that hunt the sun and the moon. They explain something Gylfi notices: the sun moves "almost as if she were afraid." Hárr tells him she has good reason. Sköll runs behind the sun and will catch her; Hati Hróðvitnisson runs ahead and wants the moon ^{Gylfaginning 12}. The sun herself is Sól, who drives the sun's horses, and her brother Máni steers the moon ^{Gylfaginning 11}.

The Ironwood brood

Snorri says these wolves come from a witch who lives east of Midgard in the forest Ironwood, who bears many giant sons in the shape of wolves. The mightiest of them is called Moon-Hound; he will gorge on the flesh of the dying, swallow the moon and spatter the sky with blood ^{Gylfaginning 12}. This draws on Völuspá, where the "giantess old in Ironwood" bears "the brood of Fenrir," one of whom will "steal the sun from the sky" ^{Völuspá 40-41}. The poem does not name the wolves. Hati's father's name, Hróðvitnir, is used for Fenrir in Lokasenna ^{Lokasenna 39}, so Hati may be Fenrir's son; no source says so outright.

At the end

At Ragnarök the chase ends: "the Wolf shall swallow the sun ... Then the other wolf shall seize the moon," and the stars vanish ^{Gylfaginning 51}. The poems are less tidy. Vafþrúðnismál gives the sun to Fenrir himself, and adds that the sun first bears a daughter who will ride her mother's paths in the new world ^{Vafþrúðnismál 46-47}. Grímnismál, the only poem to name both wolves, says that Sköll follows "the glittering god" and Hati awaits "the burning bride of heaven" ^{Grímnismál 39}; it is Snorri who spells out that one wolf hunts the sun and the other the moon.