
InNorse mythology,Ratatoskr (Old Norse, generally considered to mean "drill-tooth"[1] or "bore-tooth"[2]) is asquirrel who runs up and down theworld treeYggdrasil to carry messages between the eagles perched atop it and the dragonNíðhöggr who dwells beneath one of the three roots of the tree. Ratatoskr is attested in thePoetic Edda, compiled in the 13th century from earlier traditional sources, and theProse Edda, written in the 13th century bySnorri Sturluson.
The nameRatatoskr contains two elements:rata- and-toskr. The elementtoskr is generally held to mean "tusk".Guðbrandur Vigfússon theorized that therati- element means "the traveller". He says that the name of the legendary drillRati may feature the same term. According to Vigfússon,Ratatoskr means "tusk the traveller" or "the climber tusk."[3]
Sophus Bugge theorized that the nameRatatoskr is aloanword fromOld English meaning "Rat-tooth." Bugge's basis hinges on the fact that the-toskr element of the compound does not appear anywhere else in Old Norse. Bugge proposed that the-toskr element is a reformation of the Old English wordtūsc (Old Frisiantusk) and, in turn, that the elementRata- represents Old Englishræt ("rat").[4]
According to Albert Sturtevant, "[as] far as the elementRata- is concerned, Bugge's hypothesis has no valid foundation in view of the fact that the [Old Norse] wordRata (gen. form ofRati*) is used inHáv[amál] (106, 1) to signify the instrument which Odin employed forboring his way through the rocks in quest of thepoet's mead [...]" and that "Rati* must then be considered a native [Old Norse] word meaning "The Borer, Gnawer" [...]".[4]
Sturtevant says that Bugge's theory regarding the element-toskr may appear to be supported by the fact that the word does not appear elsewhere in Old Norse. However, Sturtevant says that the Old Norse proper nameTunne (derived fromProto-Norse*Tunþē) refers to "a person who is characterized as having some peculiar sort oftooth" and theorizes aProto-Germanic form of-toskr. Sturtevant concludes that "the fact that the [Old Norse] word occurs only in the nameRata-toskr is no valid evidence against this assumption, for there are many [Old Norse]hapax legomena of native origin, as is attested by the equivalents in the Mod[ern] Scandinavian dialects."[5] Modern scholars have accepted this etymology, listing the nameRatatoskr as meaning "drill-tooth" (Jesse Byock, Andy Orchard,Rudolf Simek[1]) or "bore-tooth" (John Lindow[2]).

In thePoetic Edda poemGrímnismál, the godOdin (disguised asGrímnir) says that Ratatoskr runs up and down Yggdrasil bringing messages between the eagle perched atop it and Níðhöggr below it:
- Old Norse:
- Ratatoskr heitir íkorni,
- er renna skal
- at aski Yggrdrasils;
- arnar orð
- hann skal ofan bera
- ok segia Níðhöggvi niðr.
- Benjamin Thorpe translation:
- Ratatösk is the squirrel named, who has run
- in Yggdrasil's ash;
- he from above the eagle's words must carry,
- and beneath the Nidhögg repeat.[6]
- Henry Adams Bellows translation:
- Ratatosk is the squirrel who there shall run
- On the ash-tree Yggdrasil;
- From above the words of the eagle he bears,
- And tells them to Nithhogg beneath.[7]
Ratatoskr is described in theProse Edda'sGylfaginning's chapter 16, in whichHigh states that
An eagle sits at the top of the ash, and it has knowledge of many things. Between its eyes sits the hawk called Vedrfolnir [...]. The squirrel called Ratatosk [...] runs up and down the ash. He tells slanderous gossip, provoking the eagle and Nidhogg.[8]
According toRudolf Simek, "the squirrel probably only represents an embellishing detail to the mythological picture of the world-ash inGrímnismál".[9]Hilda Ellis Davidson, describing the world tree, states the squirrel is said to gnaw at it—furthering a continual destruction and re-growth cycle, and posits the tree symbolizes ever-changing existence.[10]John Lindow points out that Yggdrasil is described as rotting on one side and as being chewed on byfour harts and Níðhöggr, and that, according to the account inGylfaginning, it also bears verbal hostility in the fauna it supports. Lindow adds that "in the sagas, a person who helps stir up or keep feuds alive by ferrying words of malice between the participants is seldom one of high status, which may explain the assignment of this role in the mythology to a relatively insignificant animal".[2]
Richard W. Thorington Jr. and Katie Ferrell theorize that "the role of Ratatosk probably derived from the habit of European tree squirrels (Sciurus vulgaris) to give a scolding alarm call in response to danger. It takes little imagination for you to think that the squirrel is saying nasty things about you."[11]
Ratatoskr is a character inMarvel Comics, first introduced byRyan North inThe Unbeatable Squirrel Girl.[12] Ratatoskr is depicted as possessing shapeshifting abilities and the ability to cause discord.[13]
In the video gameLa-Mulana 2, Ratatoskr is a recurring boss enemy. While initially weak, he becomes stronger and gains more abilities in subsequent battles. Within the game's mythos, Ratatoskr is an illusion created byHræsvelgr, who is trapped in the Eternal Prison.
Ratatoskas (sic) are characters inKatherine Rundell's novelImpossible Creatures.[14]
Ratatoskr appears as a playable character inSmite.[13]
Ratatoskr is an original character from the mobile gameFire Emblem Heroes and is a lead character in the 8th book of the story.
Ratatoskr is featured as a prominent side character in the 2022 video gameGod of War Ragnarök. A ghostly version of Ratatoskr appears in the preceding titleGod of War as an ally ofAtreus.[15]
Songs about Ratatoskr are featured onÝdalir, the sixth album of Icelandicviking metal bandSkálmöld and onFimbulvinter, the third album of Swedishviking metal bandBrothers of Metal.
InOne Piece, Ragnir, Loki'sMjölnir-inspired Warhammer, can take the form of a squirrel.[16]
Turns out, this new squirrel on the scene isn't a hero at all! She's an escaped god-squirrel from Asgard called Ratatoskr who's here to wreak havoc.
On June 2 this year, Ratatoskr was added to the roster (music warning on the last link)...While the Smite version of Ratatoskr seems to cast the squirrel in a heroic, if trickster-y light (or at least as much as one can be in an essentially plot-less game), the comic book version is decidedly a bad guy, using her magically enhanced skills as a gossip to sow discord in both the masses and throughout Marvel's superhero populace.
Ratatoskr makes his first proper appearance in God of War Ragnarok, but he was present in the previous game as well. In that game, Atreus could summon a spectral representation of Ratatoskr to aid them by bringing items.
When Loki defeated Ragnir, the mythical hammer transformed into a squirrel hybrid with a hammerhead. This moment proved that this hammer has consumed a Devil Fruit, most likely a Mythical Zoan.