In Norse mythology, Bölþorn or Bölþor is a jötunn, the father of Bestla, and therefore grandfather of the gods Odin, Vili and Vé. The figure receives mention in the Poetic Edda, composed in the 13th century from earlier traditional sources, and the Prose Edda, compiled by Icelander Snorri Sturluson in the 13th century. Scholars have noted that the Poetic Edda mention may mean that he is the father of the wise being Mímir.
The form Bölþor occurs in the Poetic Edda poem Hávamál, whereas Bölþorn occurs in the Prose Edda. Whereas the latter compound noun would clearly mean 'evil-thorn' to Old Norse speakers, Bölþor would have no clear meaning to medieval Scandinavians.
- Nine mighty songs I got from the son
- Of Bolthorn, Bestla's father;
- And a drink I got of the goodly mead
- Poured out from Othrorir.
The Prose Edda section Gylfaginning says that Bölþorn is Bestla's father, and adds that he is a jötunn.