|Location||East of the Misty Mountains, south of Ered Mithrin|
|Realms||Woodland Realm, Dol Guldur|
|Inhabitants||Spiders, Wood-elves, Orcs, Nazgûl|
|Description||Deep, thick, dark forest|
|Other names||Greenwood the Great, Taur-nu-Fuin, Eryn Lasgalen|
|Etymology||Anglicized Westron mirk + wood|
|Events||Fall of Dol Guldur|
Sea-danes and Goths, Swedes and Northmen,
Franks and Frisians, folk of the islands,
Swordmen and Saxons, Swabes and English,
and the Langobards who long ago
beyond Myrcwudu a mighty realm
and wealth won them in the Welsh countries
where Ælfwine Eadwine's heir
in Italy was king. All that has passed.
Mirkwood also appears in the Middle-earth fiction, as the names of two distinct forests.
In the Lord of the Rings and associated writings, Mirkwood is used as a translation of the unknown Westron name for the great forest in Rhovanion. The forest held the dwelling of a Silvan Elven kingdom, ruled by King Thranduil. It had been called Greenwood the Great until around the year 1050 in the Third Age of the Years of the Sun, when a shadow of the dark lord Sauron fell upon it, and men began to call it Taur-nu-Fuin and Taur-e-Ndaedelos in the Sindarin tongue. Sauron established himself at the hill-fortress of Dol Guldur on Amon Lanc, and drove Thranduil and his people ever northward, so that by the end of the Third Age they were a diminished and wary people, who had entrenched themselves beyond the Mountains of Mirkwood (Emyn Fuin, formerly the Emyn Duir or "Dark Mountains"). The Old Forest Road or Old Dwarf Road crossed the forest east to west, but due to its relative proximity to Dol Guldur, the road was mostly unusable. The Elves made a path farther to the north, which ended somewhere in the marshes south of the Long Lake of Esgaroth.
Mirkwood in The Silmarillion
In The Silmarillion, the highlands of Dorthonion eventually fell under Morgoth's spell, and was renamed to Taur-nu-Fuin ("Forest under Deadly Nightshade") in Sindarin, a name which Tolkien translated as Mirkwood in English. Along with the rest of Beleriand this forest disappeared after the cataclysm of the War of Wrath, although part of its peaks may have survived as an island far of the coast of Lindon.
Mirkwood in The Hobbit
In The Hobbit, Bilbo Baggins, along with Thorin Oakenshield and his band of Dwarves, ventured into Mirkwood during their quest to regain Erebor from the Dragon Smaug. There, they came across many great spiders, the breed of Shelob. Shortly after the Dwarves' escape, they were captured by the Elves. After or during these events the White Council attacked Dol Guldur, and Sauron fled to Mordor, and his influence in Mirkwood diminished for a while.
Mirkwood in the The Lord of the Rings
Sometime after losing the One Ring in The Hobbit, Gollum left the Misty Mountains to try to find it. He was captured by servants of Sauron and interrogated, then released. After his release from Mordor, he was captured by Aragorn and brought as a prisoner to Thranduil's halls. He escaped during an Orc raid, and fled south to Moria.
During the War of the Ring, Dol Guldur sent troops to attack Lorien to the West, and Thranduil's halls to the far North. Lorien was assaulted three times by Dol Guldur with failure and Thranduil lead a great battle under the trees and was victorious. Celeborn lead his forces across the Anduin from Lorien, while Thranduil lead his from the North to attack Dol Guldur for the last time. Galadriel threw down the gates of the stronghold and the darkness was lifted from Mirkwood, and it became known again by its old name of Eryn Lasgalen, Sindarin for the Wood of Greenleaves.
Mirkwood After the War of the Ring
Celeborn expanded Lorien with the addition of Southern Mirkwood which became known as East Lorien, and Thranduil's realm went as far south as the Mountains of Mirkwood. The land in between was given to the Beornings and Woodmen.