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. Those Elves captured by the Hunter were thought to have been corrupted by Melkor to form the race of Orcs.
Perhaps the Hunter was one of the "shadows and evil spirits" sent by Melkor to spy upon and harass the Quendi.[1] The Hunter may also have been Melkor himself in an attempt to deceive the Elves into thinking that the Valar were in fact evil.