Not of This Earth (1957)

After a nuclear war, the people of the planet Davanna suffer from an incurable blood disease. One of its citizens is sent to Earth to examine the blood of the human species on its usefulness for Davanna's dying race. The intruder has adopted the name Mr. Johnson, conspicuous only for his oversensitive ears and his sunglasses, which he wears even in the dark. The sunglasses hide his blank, white-eyed stare which kills his victims by burning their visual organs and brains.

Johnson hires nurse Nadine to look after him in his house. Her boss Dr. Rochelle is under Johnson's hypnotic spell after he found out about his patient's peculiar blood cell structure. Johnson's plans are disturbed by the sudden appearance of a woman from Davanna. She asks him for an instant transfusion because her physical condition has decreased rapidly. Johnson breaks into Rochelle's office, but by accident he steals a probe of a rabid dog. The Davanna woman collapses in the street and dies at the hospital. Nadine's friend, police patrol man Sherbourne, tries to question Rochelle, but the doctor is speechless under Johnson's spell. Johnson kills Rochelle for cautionary reasons, but Nadine, the next person in danger, manages to call the police. Johnson flees in his car, followed closely by Sherbourne on his motorcycle. When Sherbourne rings his siren, Johnson, distracted by the sound, drives the car off the road and dies in the crash.

After Johnson's funeral, Sherbourne and Nadine stand by his grave, which bears the inscription "Here lies a Man who was not of this Earth". While Sherbourne expresses mild compassion for Johnson, whose driving force was the rescue of his planet and its populace, Nadine refuses any kind of pity. They leave the gravesite. A mysterious man appears at the site, walking straight towards the viewer. Like Johnson, he wears the same sunglasses and carries the same distinctive case (which contains transfusion equipment).