frost-giant
Þrúðgelmir
A primeval frost-giant named once in Vafþrúðnismál: son of Aurgelmir and father of Bergelmir, in the generation between the first giant and the survivor of the flood.
Þrúðgelmir appears in a single line. When Odin, disguised in Vafþrúðnismál, asks the giant Vafþrúðnir which giant was "first fashioned of old, and the eldest of Ymir's kin" Vafþrúðnismál 28, the answer is a three-generation pedigree: Bergelmir was born countless winters before the earth was made, "Thruthgelmir's son" and "Aurgelmir's grandson" Vafþrúðnismál 29.
That is everything the sources state. Snorri does not mention Þrúðgelmir in Gylfaginning, although he quotes the neighbouring stanzas and identifies Aurgelmir with Ymir Gylfaginning 5. On that reading Þrúðgelmir is Ymir's son, the generation between the first being and Bergelmir.
A few stanzas later the poem tells how the first giant, who had no mate, produced children from his own body: a man and a maid under his arms, and from his feet "a son that six heads bore" Vafþrúðnismál 33. Many commentators identify this six-headed son with Þrúðgelmir, since he is the only son of Aurgelmir the poem names. The text never makes the link, so it remains a reasonable guess rather than a fact.
In the sources
Quoted from the hosted translations; each line is checked against the text when the site is built. Select a reference to read it in context.
Winters unmeasured ere earth was made Was the birth of Bergelmir; Thruthgelmir's son was the giant strong, And Aurgelmir's grandson of old.
And foot with foot did the wise one fashion A son that six heads bore.