Xelatian
From Memory Alpha, the free Star Trek reference
Xelatians were a humanoid species and members of the United Federation of Planets during the late 23rd century. Xelatians were distinguished in appearance by the metallic gold faceplate used to cover all portions of their face with only a small area for viewing where the eyes would ordinarily be. (Star Trek IV: The Voyage Home)
The name for this species comes from the FASA Star Trek IV Sourcebook Update book, however, this information has never been mentioned on-screen.
