"The Forms of Things Unknown" is an episode of the original The Outer Limits television show. It first aired on 4 May 1964, and was the final episode of the first season. It was filmed in a dual format as both a regular episode of "The Outer Limits" and as a pilot episode for a possible series called "The Unknown". The opening and closing narration listed here are only in "The Unknown" version and not in the broadcast The Outer Limits episode. There are plot differences between the two versions as well.

There is a fear that is unlike all other fears. It has a special, clammy chill, a deadly gift for inspiring deeper, darker dread. It is the fear of unentered rooms, of bends in lonely roads. It is the fear of the phone call in the middle of the night, of the stranger you recognize, perhaps from a nightmare. It is the fear of the unexpected, the unfamiliar. It is the fear of... THE UNKNOWN.

The plot involves two women who kill a blackmailer. Driving through the countryside with the body in the trunk, looking for a good place to bury him, they take refuge from a storm in a house containing a blind man and a strange young inventor who is experimenting with time. Unlike the traditional "time travel" devices, this one is intended to "tilt the cycles of time" and bring the dead back to life...which is what happens to the murdered blackmailer.

The story begins in the French countryside, where a car can be seen driving at high speed. The driver, Andre Pavan a wealthy playboy, is kissing his girlfriend Kassia Paine while Kassia's friend Leonora Edmond sits in the back seat.

Andre decides to stop at a small lake for a swim, stripping down to his swim trunks. He orders the women to make him a drink, and they do so – but lace the cocktail shaker with a leaf from the deadly Thanatos plant. Andre, with jovial cruelty, makes the women serve his drink while he stands in the water, ruining their "fine stilletto heels" as he puts it. He drinks a toast to blackmailing Leonora's father in London, and dies immediately, but with a strange smile on his face.

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