Beta (The Ship of Monsters)

Beta is one of the main characters in the 1960 Mexican Science Fiction film "The Ship of Monsters". She is assigned as Gamma's companion by the Regent of Venus on Gamma's mission to acquire Males for Venusians to procreate with. She's foreign to the planet, but has gained the trust of the Venusians and Gamma counts her as a close friend. It's revealed little by little in the film that she's a Uranite (from Uranius) and a Vampire. Gamma knew of this but had long trusted her friend to have self control knowing that to drink the blood of Humans is against Intergalactic Law and to do so would condemn Beta to death. However, on Earth, Beta looses control killing and feeding upon a farm hand in Chihuahua, Mexico- Gamma terrified reports this to the Regent of Venus who reminds Gamma of the punishment; disintegration. The Robot Tor is sent to retrieve Beta and Beta begs the machine to let her stay, that she doesn't want to go back but the robot transports her to the vessel. With her life on the line Beta tricks but does not kill her friend and takes command of the spaceship. She frees the male captives and declares that she intends to subjugate the Earth in the name of her ancestors (vampires). She promises the Prince of Mars, one of the Males, that she'll become his bride as they both know the sustenance of Human blood. But she makes a similar promise to an Earthman; she met her end when she became impaled by a broken tree branch while attempting to feed upon Gamma who at that point was intent on killing all the captured males and Beta. While Beta was defeated (and thus executed) the actions of Gamma had effectively failed their mission.