During the First Age and the rule of the first temple in Hildorien Melkor had decided to take a few selected mortals and to sorcerously "change" them by giving them just a tiny glint of his own radiance, warping them, making them taller, stronger and more imposing.These were the "Hănmani" (Me."Exalted ones") who became Melkor's first priests, priest-kings and temple guards.
Later, as His power had waned, he ceased to waste his own power on mortals and transmitted it unto his creatures only instead, the dragons for example.However the dark seed had been sown and the "morgothic element" continued to exist forth among mankind, making it an irredeemingly fallen race.
After Morgoth had been banished his pupil Sauron continued to distribute gifts among his mortal servants, but lacking the sheer might of his master he confined unto handing out artifacts such as his rings of power or morgûl-blades or teaching them sorcery instead of giving away from his own powers.
So Sauron created Sorcerers and Undead but no more new "Giants" among men.
see:
Known Hănmani[]
Aroch Artsír Âsriël Ashrâm Dúar Erén Habu Hethron Hormur Indrû Kalion of Angband Kashai Khorazir Môrazra Shûlan-Yîwan Udûnphel Ulcham Uráth
Notes[]
Melkor distributing some of his own might among mankind is alluded to in the Athrabeth Finrod ah Andreth, though it is never described in detail.A much similar plot including "warped men" serving Melkor at his temple in Hildorien however was developed for the "Silm film" fanfiction project.
Melkor giving away some of his radiance to men to reflect could be vaguely compared to the High elves being filled with and changed by the "light of Aman" from just visiting the Immortal lands and being exposed to the light of the two trees and the shine of the Valar, or to the Númenóreans being "gifted" by the Elves and Valar, becoming taller, stronger, more beautiful,and long-lived.It seems possible that those "Changed men" also lived in both "Worlds", visible Arda and the shadow-realm, possibly condeming them to become wraiths after death, similar to the Nazgûl.