They are first encountered in Cirith Gorgor escorting their master as he fulfils his role as Mouth of Sauron. One of them carries a banner of the Eye. Another, who unlike the others wears armour instead of robes, presents the three tokens of Frodo's capture. They do not speak in these proceedings.
They appear to be living Men, but the robed knights move in a wraith-like manner. Kathanûl is a Vile Knight who can be fought in the Bones of Barad-dûr and is considered a wraith. It is possible they are in a state between living and Unseen, like Amdir was at the time he was locked up by the Blackwolds.
Yadêphal, who serves as an emissary of Dulgabêth after the former Mouth appoints himself Sauron's Heir, might also be one of these knights.
- "Do not tarry here long or you will regret challenging the word of Dulgabêth!"