|Place from J. R. R. Tolkien's legendarium|
|Description||Cold, rainy, fertile region|
|Location||Northwest of Beleriand, between the Ered Wethrin and Ered Lómin|
Hithlum was separated from Beleriand proper by the Ered Wethrin mountain chain, and was named after the sea mists which formed there at times: Hithlum is Sindarin for "Mist-shadow"; its Quenya counterpart is Hísilómë (IPA: [ˌhiːsiˈloːmɛ], archaically IPA: [ˌxiːθiˈloːmɛ]).
The Ered Wethrin ("Mountains of Shadow") formed the southern and eastern wall, and had only a few passes; as such they formed a natural defensive line. The western wall was formed by the Ered Lómin or "Echoing Mountains", which curved north-westward to the Helcaraxë.
The land of Lammoth lay west of the Ered Lómin and was not part of Beleriand or Hithlum. The land of Nevrast was separated from Hithlum by the southern part of the Ered Lómin range. Nevrast was usually seen as part of Hithlum, but its climate was that of Beleriand.
Hithlum was cold and rainy, but quite fertile. The Noldor landed here in the Firth of Drengist and first camped at the shores of Lake Mithrim.
Later in the First Age, Hithlum was continually under attack by Morgoth, finally being lost after the Nírnaeth Arnoediad. The Hadorians were scattered, killed, or enslaved, the Noldor were enslaved in Morgoth's mines if they could not flee in time, and Morgoth trapped the Easterlings there.
Hithlum was completely destroyed during the War of Wrath.
Mithrim formed a part of Hithlum, and was the south-eastern corner of it, bordering Dor-lómin to the west, from which it was divided by the Mountains of Mithrim. Mithrim's climate was the same as Hithlum's, the air was cool and the winters were cold but it was a fair land.
The area was home to a great lake, the Lake of Mithrim, which was the body of water north of Beleriand where the Noldor first dwelt in Middle-earth: the Sons of Fëanor on the northern shore and Fingolfin's host on the southern shore.
The Noldor dwelt here for a while until their feud was healed, and they removed to other lands. Mithrim was also home to Sindarin Elves, who soon mingled with the Noldor after they had learned Sindarin.
Dor-lómin, "Land of Echoes", was the south-western part of Hithlum, bordered in the east by the Mountains of Mithrim, and in the north by the river which formed the Rainbow Cleft known as Annon-in-Gelydh, or "Gate of the Noldor".
It was first colonized by the Noldor shortly after they arrived in Middle-earth, and for a long time was ruled by Fingon son of Fingolfin, before he took over as High King of the Noldor after his father was killed.
Húrin son of Galdor, the last Edain lord of Dor-lómin dwelt in its south-western corner, near the mountain known as Amon Darthir, where the river Nen Lalaith began. After the Nírnaeth Arnoediad, when the House of Hador was destroyed or scattered, Easterlings dwelt in Dor-lómin, and Tuor — Húrin's orphaned nephew — was fostered by the Elves of Androth in the nearby Mountains of Mithrim.
Like the rest of Hithlum Dor-lómin was destroyed during the War of Wrath.