The Thief from Outer Space

Will tells his family what happened, but they do not quite believe him. Later, Will goes out exploring for evidence to prove his story true. He finds a strange, sedan chair-like vehicle, and gets inside. He is then transported through space to an asteroid where the thief and his slave live.
The slave catches Will and hides him away in a furnace room, threatening to feed him to lions unless he does the slave’s work. Meanwhile, the Robinsons wonder about the strange celestial body orbiting their planet and the absence of Will.
Ali discovers his slave has been hiding Will. He treats Will decently enough, giving him food and making him an assistant. The thief explains to Will that he is seeking a very special magical treasure, a beautiful princess who had been kidnapped long ago. The device he uses to track her has led him to the planet the Robinsons are on.
The thief visits the Robinsons and asks who they are, but Will lies and says they are not his family, they are his enemies. Penny arrives on the asteroid, and Smith shortly thereafter. Penny is forced to work in the furnace room, and Smith is tied to a board under a swinging pendulum blade. The thief demands Smith tell him where the princess is, but Dr Smith is terrified and truthfully says he does not know.
Will and Penny come up with a way to trick Ali, claiming their father has a treasure map which might have made the locator device indicate their location. The thief believes them and the three go down to the planet. As this is happening, the slave rescues Smith and shows him an ancient book which indicates a person bearing an uncanny resemblance to him is his true master.
The children’s plan works, and the thief himself is captured. He finds out the treasure map is a fake, and descends into a rage until Dr Smith distracts him by showing up dressed as a vizier. Smith commands his new slave to kill the thief. The slave is destroyed by one of Ali’s rings.
The thief is about to kill Dr Smith when he recognizes the golden bottle Penny found. It turns out the beautiful princess is trapped inside. Much to Ali’s shock and disappointment the once beautiful princess emerges from her bottled imprisonment aged and plump. It quickly becomes clear she is also lazy and has a complaining nature. Ali sends her back into the bottle and then leaves the scene himself in a puff of smoke.
Ps.
The slave character was played by 206 cm (6 ft 9 inches) actor Ted Cassidy (1932 – 1979). His most famous acting role was Lurch in THE ADAMS FAMILY (1964 – 1966). He also featured in a number of STAR TREK (1966 – 1969) and I DREAM OF JEANIE (1965 – 1970) episodes as well as providing the growls and roars of the Hulk in the television series THE INCREDIBLE HULK (1977 – 1982).
The narration you can hear in the video below for the opening title sequence of THE INCREDIBLE HULK belongs to Ted Cassidy. He died at the age of 49.