It Conquered the World

It Conquered the World is an independently made 1956 American blackandwhite science fiction film, produced and directed by Roger Corman, starring Peter Graves, Lee Van Cleef, Beverly Garland and Sally Fraser. The film was distributed by American International Pictures.

After killing a flying batlike creature which carries the mind control device, Dr. Nelson returns home to find his wife newly assimilated. She then attempts to force his own assimilation using another batcreature in her possession, and he ends up being forced to kill her in selfdefense. By then, the only people who are still free from Zontars influence are Nelson, Anderson, Andersons wife, and a group of army soldiers on station in the nearby woods.Nelson finally persuades the paranoid Anderson that he has made a horrible mistake in blindly trusting Zontars motives, allying himself with a creature bent on world domination. When they discover Toms wife has taken a rifle to the aliens cave in order to kill it, they hurriedly follow her but the creature kills Claire Anderson before the two doctors can rescue her. Finally, seeing the loss of everything he holds dear, Dr. Anderson viciously attacks Zontar by holding a blowtorch to the creatures face Anderson dies at the aliens hand as it expires. ........

Source: Wikipedia