In Norse mythology

Norse mythology

Norse mythology, a subset of Germanic mythology, is the overall term for the myths, legends and beliefs about supernatural beings of Norse pagans. It flourished prior to the Christianization of Scandinavia, during the Early Middle Ages, and passed into Nordic folklore, with some aspects surviving...

, Þrívaldi (anglicized as Thrívaldi or Thrivaldi), whose name means "thrice mighty", is a giant killed by Thor

Thor

In Norse mythology, Thor is a hammer-wielding god associated with thunder, lightning, storms, oak trees, strength, the protection of mankind, and also hallowing, healing, and fertility...

.

This fact is mentioned by Snorri Sturluson

Snorri Sturluson

Snorri Sturluson was an Icelandic historian, poet, and politician. He was twice elected lawspeaker at the Icelandic parliament, the Althing...

 in the Skáldskaparmál

Skáldskaparmál

The second part of Snorri Sturluson's Prose Edda the Skáldskaparmál or "language of poetry" is effectively a dialogue between the Norse god of the sea, Ægir and Bragi, the god of poetry, in which both Norse mythology and discourse on the nature of poetry are intertwined...

(4), according to which "killer of Þrívaldi" ("vegandi Þrívalda") is a kenning

Kenning

A kenning is a type of literary trope, specifically circumlocution, in the form of a compound that employs figurative language in place of a more concrete single-word noun. Kennings are strongly associated with Old Norse and later Icelandic and Anglo-Saxon poetry...

for Thor. Snorri quotes one stanza by Bragi Boddason

Bragi Boddason

In his Edda Snorri Sturluson quotes many stanzas attributed to Bragi Boddason the old , a court poet who served several Swedish kings, Ragnar Lodbrok, Östen Beli and Björn at Hauge who reigned in the first half of the ninth century...

, who calls Thor "cleaver apart of Þrívaldi's nine heads" ("sundrkljúfr níu höfða Þrívalda"), and another stanza by Vetrliði Sumarliðason

Vetrliði Sumarliðason

Vetrliði Sumarliðason is a 10th century Icelandic skald.He was the great-grandson of Ketill hængr , one of the settlers of Iceland. He lived in Fljótshlíð, in the south of the island....

 who praises Thor for having battered ("lemja") Þrívaldi.

Þrívaldi is also listed in the þulur.