The Blank Faced Aliens, appeared in the episode "The Tale of the Thirteenth Floor".
They are friendly and civilized beings from an unknown planet, that is apparently a beautiful paradise. They can see
beyond the horizon and fly like birds. They also have telekinesis and some of them are organic and some are robotic. They have blank faces with no facial features and they only have three fingers on each hand.
When they travel to Earth, they need to constantly charge up on a supplement of their plants atmosphere. This takes about ten years to store an amount to maintain their appearance and keep their powers. The robotic ones can be turned on and off by means of a remote control. When they receive too much exposure from another planet's atmosphere, they instantly gain a human appearance. One that is complete with a full head of hair. If they are aware of this, they can pull it if at any given time.
If a being of their race is left on another planet by mistake, they plan a rescue for it. A rescue mission takes about ten years to store up enough atmosphere to maintain a safe and sound trip. When they find the lost being, they will expose them to a store up amount of their planet's atmosphere. Then they will give him or her a series of tests to help them regain their proper senses and powers. Also it is to help them become able to survive on their planet before letting them onto the ship to return them home.
In the year 1983, a couple named Olga and Raymond (who's robotic) had visited Earth. However, they mistakenly left their daughter behind. Then soon enough, from exposure to earth's atmosphere, their daughter lost her powers and gained a human appearance. She was soon adopted by a human family and renamed Karin.
Then ten years later, in 1993 Raymond and Olga contacted Karin with messages on the television. She thought these were dreams and had no idea of what was happening. Olga and Raymond along with their pleasant friend Leonid returned to earth, after having stored up enough of their own atmosphere. They contacted Karin inviting her to come upstairs to the thirteenth floor of her apartment building. They did this under the pretense it was a new toy factory opening up.
Karin arrived, but they were unaware that she brought her adoptive brother Billy with her. Karin played the games and quickly from taking the exposure to their own atmosphere. However it scared Karin and she ran off and escaped. Leonid tried his best to convince her, but she didn't believe him.
After they took off on their spaceship, Olga contacted Karin and nicely explained to her that it hasn't been a dream. This was supposed to be her rescue, since they left her behind by mistake. Then she explained that they wouldn't be able to come again for another ten years and changed back with the last of her atmosphere. Then suddenly from exposure to the atmosphere on the ship, Karin pealed off her human skin to reveal her true from scaring the wits out of her brother.