In Faceless, Conduits are people who have an unknown connection to The Being, allowing it to use them to its advantage. The Being used to use Conduits in order talk to people or to help kidnap people in order for The Being to withdraw their souls and place them into Dolls. (Which are built to store Dolls for longer durations without decay.) However, there are no known Conduits left in existence as the last of them were believe to be members of Daniel North's family who eventually worked the NHI in order to defect against the Being, which led to their deaths.
Grace 'Gray' North.
Grace North is Daniel and Edward's Sister, it is believed she is a Conduit who has been constantly protected by Daniel to prevent her from being killed by other hunters. The Company that enforced the NHI were determined to secure all Conduits in order to prevent The Being from executing mass-kidnappings, however, Grace was an illegitimate child hidden for many years until Daniel learnt from Grace's mother that she had shown signs of being a Conduit.