The Hunter (creature)
From Tolkien Gateway
The Hunter was a shadowy creature of Elvish legend, said to have plagued the newly-awakened Elves at Cuiviénen.[1]
The true identity of the Hunter is unknown. The legend could have had its source in lies spread by Melkor about Oromë, in an attempt to deceive the Elves into thinking that he was evil. Or maybe the Hunter was one of the "shadows and evil spirits" sent by Melkor (or perhaps even Melkor himself) to spy upon and harass the Quendi.[1]
See also