Odin is a prominently mentioned god throughout the recorded history of the Germanic peoples, from the Roman occupation of regions of Germania through the tribal expansions of the Migration Period and the Viking Age. In the modern period, Odin continued to be acknowledged in the rural folklore of Germanic Europe. References to Odin appear in place names throughout regions historically inhabited by the ancient Germanic peoples, and the day of the week Wednesday bears his name in many Germanic languages, including English.
In Old English texts, Odin holds a particular place as a euhemerized ancestral figure among royalty, and he is frequently referred to as a founding figure among various other Germanic peoples, including the Langobards. Forms of his name appear frequently throughout the Germanic record, though narratives regarding Odin are mainly found in Old Norse works recorded in Iceland, primarily around the 13th century. These texts make up the bulk of modern understanding of Norse mythology.
In Old Norse texts, Odin is depicted as one-eyed and long-bearded, frequently wielding a spear named Gungnir, and wearing a cloak and a broad hat. He is often accompanied by his animal companions and familiars—the wolves Geri and Freki and the ravens Huginn and Muninn, who bring him information from all over Midgard—and rides the flying, eight-legged steed Sleipnir across the sky and into the underworld. Odin is the son of Bestla and Borr and has two brothers, Vili and Vé. Odin is attested as having many sons, most famously the gods Thor (with Jörð) and Baldr (with Frigg), and is known by hundreds of names. In these texts, he frequently seeks greater knowledge, at times in disguise (most famously by obtaining the Mead of Poetry), makes wagers with his wife Frigg over the outcome of exploits, and takes part in both the creation of the world by way of slaying the primordial being Ymir and giving the gift of life to the first two humans Ask and Embla. Odin has a particular association with Yule, and mankind's knowledge of both the runes and poetry is also attributed to him, giving Odin aspects of the culture hero.
In Old Norse texts, female beings associated with the battlefield—the valkyries—are associated with the god and Odin oversees Valhalla, where he receives half of those who die in battle, the einherjar. The other half are chosen by the goddess Freyja for her afterlife location, Fólkvangr. Odin consults the disembodied, herb-embalmed head of the wise being Mímir for advice, and during the foretold events of Ragnarök, Odin is told to lead the einherjar into battle before being consumed by the monstrous wolf Fenrir. In later folklore, Odin appears as a leader of the Wild Hunt, a ghostly procession of the dead through the winter sky. He is associated with charms and other forms of magic, particularly in Old English and Old Norse texts.
Odin is a frequent subject of study in Germanic studies, and numerous theories have been put forward regarding his development. Some of these focus on Odin's particular relation to other figures; for example, the fact that Freyja's husband Óðr appears to be something of an etymological doublet of the god, whereas Odin's wife Frigg is in many ways similar to Freyja, and that Odin has a particular relation to the figure of Loki. Other approaches focus on Odin's place in the historical record, a frequent question being whether the figure of Odin derives from Proto-Indo-European religion, or whether he developed later in Germanic society. In the modern period, Odin has inspired numerous works of poetry, music, and other forms of media. He is venerated in most forms of the new religious movement Heathenry, together with other gods venerated by the ancient Germanic peoples; some branches focus particularly on him.
The Old Norse theonymÓðinn (popularly anglicised as Odin) and its cognates, including Old EnglishWōden, Old SaxonWōden, and Old High GermanWuotan, derive from the reconstructed Proto-Germanic theonym *wōđanaz. The masculine noun *wōđanaz developed from the Proto-Germanic adjective *wōđaz, related to Latinvātēs and Old Irishfáith, both meaning 'seer, prophet'. Adjectives stemming from *wōđaz include Gothicwoþs 'possessed', Old Norse óðr, 'mad, frantic, furious', and Old English wōd 'mad'.
The adjective *wōđaz (or *wōđō) was further substantivised, leading to Old Norse óðr 'mind, wit, soul, sense', Old English ellen-wōd 'zeal', Middle Dutchwoet 'madness' (modern Dutch:woede 'anger'), and Old High German wuot 'thrill, violent agitation'. Additionally the Old Norse noun æði 'rage, fury' and Old High German wuotī 'madness' derive from the feminine noun *wōđīn, from *wōđaz. The weak verb *wōđjanan, also derived from *wōđaz, gave rise to Old Norse æða 'to rage', Old English wēdan 'to be mad, furious', Old Saxon wōdian 'to rage', and Old High German wuoten 'to be insane, to rage'.
Over 170 names are recorded for Odin. These names are variously descriptive of attributes of the god, refer to myths involving him, or refer to religious practices associated with the god. This multitude of names makes Odin the god with the most names known among the Germanic peoples.
The modern English weekday name Wednesday derives from Old English wōdnesdæg. Cognate terms are found in other Germanic languages, such as Middle Low Germanwōdensdach (Dutch woensdag), and Old NorseÓðinsdagr (Danish, Norwegian and Swedish Onsdag). All of these terms derive from Proto-Germanic *Wodensdag, itself a Germanic interpretation of Latin Dies Mercurii ("Day of Mercury"). In Old High German, the name derived from Odin's was replaced by a translation of Church Latin media hebdomas ('middle of the week'), hence modern German Mittwoch.