The tree Yggdrasil.
https://commons.wikimedia.org/wiki/File:Yggdrasil.png
Odin was once known as Ygg.
This ash is the best and greatest of all trees; its branches spread over all the world, and reach up above heaven. Three roots sustain the tree and stand wide apart; one root is with the asas and another with the frost-giants, where Ginungagap formerly was; the third reaches into Niflheim; under it is Hvergelmir, where Nidhug gnaws the root from below. But under the second root, which extends to the frost-giants, is the well of Mimir (Mimir was beheaded but kept alive by Odins magic), wherein knowledge and wisdom are concealed.
The third root of the ash is in heaven, and beneath it is the most sacred fountain of Urd. Here the gods have their doomstead. The asas riding hither every day over Bifrost, which is also called Asa-bridge.
On one of the boughs of the ash sits an eagle, who knows many things. Between his eyes sits a hawk that is called Vedfolner. A squirrel, by name Ratatosk, springs up and down the tree, and carries words of envy between the eagle and Nidhug. Four stags leap about in the branches of the ash and bit the leaves. Thier names are: Dain, Dvalin, Duney and Durathro.
http://religion.wikia.com/wiki/Dorrudr
Dorruðr
"Spear-fighter". (a kenning for Odin)
In Norse mythology, four stags or harts (male red deer) eat among the branches of the World Tree Yggdrasill. According to the Poetic Edda, the stags crane their necks upward to chomp at the branches. Their names are given as Dáinn, Dvalinn, Duneyrr and Duraþrór. Two of the stag names, Dáinn and Dvalinn, are also dwarf names as well.
In Norse mythology, Norðri, Suðri, Austri and Vestri ("Northern, Southern, Eastern and Western") are four dwarves in the Prose Edda book Gylfaginning who each support one of the four cardinal points. Together, they uphold the heavenly dome, created from the skull of the jötunn Ymir. They probably represent the four winds
More worms lie
beneath Yggdrasill’s Ash than
any dimwit dunce may dream of:
Soil Worm and Heath Worm —
they are sons of Grave Wolf—
Grey Back and Grave Digger,
Svafnir and Ofnir —
I think they will for ever erode
the twigs of the tree.
Svafnir and Ofnir, in addition to being names of dragons (worms), are also listed as names of Odin.
Then said Ganglere: What tidings are to be told of Ragnarok? Of this I have never heard before. Har answered: Great things are to be said thereof... In the midst of this clash and din the heavens are rent in twain, and the sons of Muspel come riding through...to the plain which is called Vigrid. Thither repair also the Fenris-wolf and the Midgard-serpent. To this place have also come Loke and Hrym,. and with him all the frost-giants...The plain Vigrid is one hundred rasts on each side. (Atlantis is 256*8 stadia on each side. Each "lot" was 8 stadia square and there were 64,000 lots. In the Roman system, there were 625 feet to the stadium, eight stadia to the mile, and three miles to the league. In base 16 the number 256 is written 100.)
Heimdal stands up, blows with all his might in the Gjallar-horn and awakens all the gods, who thereupon hold counsel. Odin rides to Mimer's well to ask advice of Mimer for himself and his folk. Then quivers the ash Ygdrasil, and all things in heaven and earth fear and tremble. The asas and the einherjes arm themselves and speed forth to the battlefield. Odin rides first; with his golden helmet, resplendent byrnie, and his spear Gungner, he advances against the Fenris-wolf. Thor stands by his side, but can give him no assistance, for he has his hands full in his struggle with the Midgard-serpent. Frey encounters Surt, and heavy blows are exchanged ere Frey falls. The cause of his death is that he has not that good sword which he gave to Skirner. Even the dog Garm, that was bound before the Gnipa-cave, gets loose. He is the greatest plague. He contends with Tyr, and they kill each other... Loke fights with Heimdal, and they kill each other