Tyr (pronounced like the English word “tear”; Old Norse Týr, Old English Tiw, Old High German *Ziu, Gothic Tyz, Proto-Germanic *Tiwaz, “god”) is a relatively minor Aesir god in Viking Age Norse mythology. However, his name and attributes along with evidence from the study of comparative religion divulge to us that his Viking Age form is a severely diminished version of a divine figure who, in earlier ages, was the highest god of the Norse and other Germanic peoples. (By the Viking Age, this role had been usurped by Odin.)
Tyr in the Viking Age
While mentions of Tyr in Old Norse literature are few, he certainly seems to have been regarded as one of the principal war gods of the Norse, along with Odin and Thor. For example, in the Sigrdrífumál, one of the Eddic poems, the valkyrie Sigrdrífa instructs the human hero Sigurðr to invoke Tyr for victory in battle. Another Eddic poem, the Lokasenna, corroborates this picture by having Loki taunt that Tyr could only stir people to strife, and could never reconcile them.
The Lokasenna also mentions that Tyr lost one of his hands to the wolf Fenrir. Indeed, Tyr’s one-handed-ness seems to be one of his defining attributes. The only full explanation of this handicap comes from the Prose Edda, which recounts how, when the gods endeavored to bind Fenrir for their own safety, the wolf refused to allow the suspiciously innocent-looking cord to be put around him unless one of the deities put his or her hand in his mouth as a pledge of good faith. Only Tyr was brave and honorable enough to comply with the beast’s request, and, when Fenrir found himself unable to break free of his fetters, he accordingly helped himself to the god’s hand.
The tale of the loss of his hand suggests that Tyr was appealed to not only in matters of war but also in matters involving law, justice, honor, oaths, and upholding traditional sources of authority. As will be shown below, Tyr was certainly associated with these spheres of life before the Viking Age, and the nature of his handicap shows that he was still associated with these conceptions in the Viking Age, however much his importance had been lessened amongst the northern Germanic peoples who had not yet been Christianized by this time.
Tyr Before the Viking Age
Just as the Norse languages and religion are part of the larger Germanic family of languages and religious modes, so the Germanic languages and religions are part of the larger Indo-European family, which also includes Greek, Sanskrit, the Celtic and Romance languages, and several others besides, as well as the religious traditions practiced by the speakers of those languages. One can potentially learn much about an aspect of a religious tradition that’s an offshoot of the Proto-Indo-European parent tradition by studying the parent tradition itself.
Such is certainly the case with Tyr. Tyr is a continuation of the Proto-Germanic deity *Tiwaz, who is himself a continuation of the Proto-Indo-European god *Dyeus. Both the name *Dyeus and the basic Proto-Indo-European word for god, *deiwós, are variations of the root *dyeu-, “the daytime sky.” *Dyeus was the archetypal “Sky Father” and likely the head of the Proto-Indo-European pantheon. After all, his name was effectively identical with the word for godhood itself. Other gods derived from him include the Greek Zeus and the Roman Jupiter (from *Dyeus Phater, “Sky Father”). Fascinatingly, the modern English words “day” and “deity” both come from this same root.
The use of this same word to denote both the name of *Dyeus and “god” more generally survived into the Viking Age. As was noted above, Tyr’s name simply means “god,” and its use can be found in contexts that have nothing to do with Tyr with a capital “T.” For example, one of Odin’s bynames is Hangatýr, “God of the Hanged.”
One of *Dyeus‘s roles was that of a guarantor of justice, one before whom oaths were sworn. As we’ve seen, this role remained consistent up through the Viking Age.
Some of the spatiotemporal gaps between these two distant periods are filled in with evidence from the Germanic tribes of the first few centuries CE. In the Elder Futhark, the oldest runic alphabet, the T-rune, named *Tiwaz after Tyr’s name in the Proto-Germanic language that was spoken at the time, is in the shape of an arrow pointed upward toward the heavens, which is clearly emblematic of the god’s associations with both war and the diurnal sky. The Romans glossed *Tiwaz as “Mars” due to his military role, and a third century votive stone erected by a Germanic warrior in the Roman army features an inscription dedicated to a “Mars of the Þing” (the Germanic judicial/legislative assembly); surely this is addressed to Tyr.
Also through his association with Mars, Tyr lent his name to the modern English “Tuesday,” from Old English “day of Tiw” (Tiwesdæg), which was in turn based on the Latin Dies Martis.
Thus, however humble Tyr’s place in Viking Age religion and mythology, he was once as indispensable as daylight in the minds and hearts of the Germanic peoples.
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 de Vries, Jan. 2000. Altnordisches Etymologisches Wörterbuch. p. 603.
 Orel, Vladimir. 2003. A Handbook of Germanic Etymology. p. 408.
 The Poetic Edda. Sigrdrífumál, stanza 6.
 The Poetic Edda. Lokasenna, stanza 38.
 Snorri Sturluson. The Prose Edda. Gylfaginning 25.
 Mallory, J.P., and D.Q. Adams. The Oxford Introduction to Proto-Indo-European and the Proto-Indo-European World. p. 408.
 Ibid. p. 409.
 Snorri Sturluson. The Prose Edda. Skáldskaparmál 9.
 West, M.L. 2009. Indo-European Poetry and Myth. p. 172.
 Turville-Petre, E.O.G. 1964. Myth and Religion of the North: The Religion of Ancient Scandinavia. p. 181.