Fuinur was a Black Númenórean lord.
Like all Black Númenóreans, Fuinur fell under the influence of the Dark Lord Sauron during the late Second Age while he was on the island of Númenór.
He sailed east with Herumor to the lands of Harad, and the two became lords among the Haradrim.
The name Fuinur comes from the word fuinë, meaning "deep shadow". There appears to be no definitive origin of the word fuinë, though it may have been borrowed into Quenya from Telerin.