The voice actor wasn't credited, but his voice sounded like actor Gary Raymond to me. Raymond played Moffatt in "The Rat Patrol" and guest-starred as Colonel John Grey in "The Man Who Came Back" episode of the British Science Fiction TV Series, "UFO." This episode was pretty bad and relied on comedy, which was better in episodes with weak plots and bad writing like this one. There is at least one unanswered question in this episode, too. Did Don West see the aliens who knocked him out when they entered the Jupiter-2 late at night? Also, this episode hints at an almost demonic possession of Farnum, whose soul has been sold by his agent. The idea that a being consisting of fire would find a human female beautiful and attractive is ludicrous, but fantasy and science fiction hack writers often resort to this moronic plot device. Farnum actually mention how absurd it is for a being to find a being of another species attractive in his conversation with Will Robinson, but the writer still manages to ignore his own lesson and make this the plot device that comprises the final conflict. Farnum was an outrageous, absurd character, but this series was at its best in the beginning when it was serious science fiction.