I wore the garb of the Caste of Assassins, and on the left temple of the black helmet was the golden slash of the messenger.
-Tarnsman of Gor, pg. 192

Kuurus, of the Caste of Assassins, entered the great gate of Ar. Guardsmen did not detain him, for he wore on his forehead the mark of the black dagger.
-Assassin of Gor, pg. 6