(written from a Production point of view)
Kirk Raymone, aka Kirk Raymond, is the actor who played Duur in "Friday's Child", a second season episode of Star Trek: The Original Series. He later appeared as a Cloud Guard #1 in the third season episode "The Cloud Minders".
Raymone went on to appear in the classic 1977 science fiction film Close Encounters of the Third Kind, starring Teri Garr. The following year, he appeared in the Vietnam War drama Coming Home.