The Necromancer in The Hobbit is actually Sauron, the dark lord and primary antagonist of The Lord of the Rings. Although in The Hobbit he is only referred to as the Necromancer, later writings by J.R.R. Tolkien and the appendices of The Lord of the Rings confirm that this mysterious dark sorcerer residing in Dol Guldur in southern Mirkwood is indeed Sauron in disguise
. Sauron adopted the name "the Necromancer" to conceal his identity while he rebuilt his power in secret after his defeat in the Second Age. His presence corrupted the forest of Greenwood, turning it into the dark and dangerous Mirkwood. Gandalf's concern about the Necromancer leads him to leave Thorin's company temporarily to join the White Council in driving Sauron out of Dol Guldur
. Thus, the Necromancer is a key plot device in The Hobbit , representing the growing threat of Sauron's return to power in Middle-earth, even though his role is more background and indirect compared to his central villainy in The Lord of the Rings
