faceless
When the entire front of the character's head is within the frame, but obscured or not completely drawn. Typically used on various background characters (such as a crowd of people) to deemphasize them, or on a "self-insert" character in various NSFW works who were meant to be anonymous and/or representing the reader/viewer.
If the character is meant to literally be without a face (not just for artistic style/due to concealed features; EX: slender man), use hole in face or some combination of no eyes, no nose, or no mouth. If the character's face is shaded but their eyes are still visible, uses shaded face instead.