It! The Terror from Beyond Space

One by one, the crew members of a spacecraft returning to Earth from Mars are dying at the hands of a mysterious -- and seemingly indestructible -- parasitic beast stowed away on the ship. Marshall Thompson and Dabbs Greer co-star in director Edward L. Cahn's suspenseful, sci-fi classic, which features a script penned by Jerome Bixby, the scribe behind several episodes of Star Trek and The Twilight Zone.