Gray Man:
[TDR: Glossary, 586]

Someone who has voluntarily surrendered his or her soul in order to become an assassin serving the Shadow. Gray Men are so ordinary in appearance that the eye can slide right past without noticing them. The vast majority of Gray Men are indeed men, but a small number are women.

[TDR: 15, The Gray Man, 143]

"The Soulless, the Gray Men, give up their souls to serve the Dark One as assassins. They are not really alive, after that. Not quite dead, but not truly alive. And despite the name, some are women. A very few. Even among Darkfriends, only a handful of women are stupid enough to make that sacrifice. You can look right at them and hardly notice them, until it is too late."

--Sheriam Sedai

The Chosen Speak

[TDR: 26, Daughter of the Night, 342]