|Location||East of the Misty Mountains, southeast of Mount Gundabad|
|Description||Tributary to the Anduin|
Greylin was a river of the far north of Middle-earth. The Greylin rose in the western Grey Mountains and flowed southwestward to meet the Langwell and together they formed the source of the Great River, Anduin. Between the two rivers was the old capital city of the Éothéod, Framsburg.
The second element of the name was related to Anglo-Saxon hlynn or "torrent", although its literal meaning was probably "the noisy one".