Þjálfi (Old Norse) or Þjelvar (Old Gutnish) is a farmer's son in Norse mythology who appears twice in Snorri's Edda and once in the Gutasaga. His name means Delve or Till.
Snorri relates in Gylfaginning
that when Thor
visited the boy Þjálfi's family on their way to Jötunheimr
, Þjálfi cut open the bone of one of Thor's butchered goats in order to get at the marrow. When Thor resurrected the goat, it could not walk properly. To atone for this, Þjálfi and his sister Röskva
(Reap) had to serve Thor as his thralls
, accompanying him and Loki on their journey to the land of the giants
where the boy competed in a footrace against Útgarða-Loki
's thought, Hugi
In Snorri's Skáldskaparmál, Þjálfi helped Thor in his battle against the giant Hrungnir by tricking him into standing on his own shield, telling him an attack would come from below and thus making him vulnerable to Thor's hammer. Þjálfi meanwhile easily defeated a secondary monster named Mökkurkálfi, a giant made of clay but with the "heart of a mare".
In Thórsdrápa, Þjálfi is Thor's companion on his journey to the home of the giant Geirröd, although in Snorri's version of the tale Þjálfi is replaced with Loki.
In the Gutasaga
is an adult and arrives at a magical island which sunk every night and resurfaced every day. He lit a fire on the island and from then on it sank no more. Þjelvar's son Hafþi married the girl Huítastjerna (White Star) and they became the ancestors of the Gutar
Tjelvar's Grave Image is a stone ship, which according to legend is the grave of Þjelvar, and it is dated to ca 750 BC.