Ungoliant allies with MelkorUngoliant allies with Melkor - Morgoth is generally thought to be the most evil being of the First Age.  And yet, there is one other who could match his malevolence.  She is Ungoliant, a great spirit of darkness who exists in the form of a gargantuan arachnid.  Her existence is so primeval that her origin is unknown.  However, even before the awakening of the Elves, we get a glimpse of strange beings springing up throughout Middle-earth.


"But already the oldest living things had arisen: in the seas the great weeds, and on earth the shadow of great trees; and in the valley of the night-clad hills there were dark creatures old and strong." ~The Silmarillion, chap. 3 (Of the coming of Elves)


Morgoth had a plan to strike at the heart of Valinor, but in order to do so, he had to form an uneasy alliance with the one monster he could not control.


"Now Melkor came to Avathar and sought her out; and he put on again the form that he had worn as the tyrant of Utumno: a dark lord tall and terrible.  In that form he remained ever after.  There in the black shadows, beyond the sight of Manwë in his highest halls, Melkor with Ungoliant plotted his revenge." ~The Silmarillion, chap. 8 (Of the Darkening of Valinor)


And so at a time when the Valar held a great festival and all those in Valinor were preoccupied, Morgoth led her into the heart of their realm.


"Then the Unlight of Ungoliant rose up even to the roots of the Trees, and Melkor spang upon the mound; and with his black spear he smote each tree to its core, wounded them deep, and their sap poored forth as it were their blood, and was spilled upon the ground.  But Ungoliant sucked it up, and going then from Tree to Tree she set her black beak to their wounds, till they were drained; and the poison of Death that was in her went into their tissues and withered them, root, branch, and leaf; and they died...Melkor had gone whither he would, and his vengence was achieved." ~The Silmarillion, chap. 8 (Of the Darkening of Valinor)