Tevildo

"Then the little bird sings not any more; come down or I must fetch thee, for behold, I will not encourage the Elves to seek audience of me in mockery."


 * ― Tevildo, The Tale of Tinúviel

Tevildo (Qenya; IPA: ['tevildo] - "Lord of Cats") was a close companion of Melko; he was a great cat inhabited by an evil spirit, and wore a golden collar, through which he suborned his thanes. He harboured much resentment for the dogs, especially his hated enemy Huan.

Biography
During the Quest for the Silmaril, Beren was captured by the agents of Melko; spared death, he was sent instead as a servant to Tevildo. Beren endures much disgrace and suffering due to hard labour and mockery by his oppressors. However, Tinúviel uses her guile to trick the cat into following her into the woods, where she claims Huan lies wounded; caught by surprise by the dog and defeated, Tevildo is forced to reveal the enchantment holding the castle together and yields his collar; the abode's stones crumble and the wretched souls held in thraldom are freed. Dismayed and fearing the scorn of Melko, Tevildo flees.

Trivia

 * Tevildo's conception preceeded that of Thû (later Sauron) in the early layouts of Beren and Lúthien. Except for another occurrence of the name in a mention by Rúmil ("[...] may Tevildo Prince of Cats harry him for daring to perch in a garden thas is in the care of Rúmil.", the Tale of Tinúviel is the last and only appearance of Tevildo's character in any of J.R.R. Tolkien's works.
 * Interestingly, the Eye of Sauron from Tolkien's The Lord of the Rings resembles that of an adder or a cat (the latter is perhaps meant as a refference to Tevildo as Sauron's forerunner).