The following quote is taken from Tolkien's Lays of Beleriand, specifically, the "Lay of Leithien," which tells the story of Beren and Luthien in poetic form. "Thû" is short for "Gorthû," an early name for Sauron. Technically, this poem is talking about a wolf but it seemed to fit.

Now there came slowly forth and glared
Into the night a shape long-haired,
Dank with poison, with awful eyes
Wolfish, ravenous; but there lies
A light therein more cruel and dread
Than ever wolfish eyes have fed.
More huge were its limbs, its jaw more wide,
Its fangs more gleaming-sharp, and dyed
With venom, torment, and with death.
The deadly vapor of its breath
Swept on before it. Swooning dies
The song of Lúthien, and her eyes
Are dimmed and darkened with a fear,
Cold and poisonous and drear.
Thus came Thû, as wolf more great
Than e'er was seen from Angband's gate
To the burning south, than ever lurked
In mortal lands or murder worked.