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.
Beta is shown early on to be close friends with Gamma and as Beta came from another planet other then Venus her role is guide; she takes Gamma to planets such as Mercury, Mars, 'the Dead Planet', and others. The two along with the Robot Tor whom they picked up on 'the Dead Planet' only land on Earth on their way back to Venus when one of their engines break; the planet is stated to be Antarias by Tor who states that the planet; while full of people that seem bent on destroying it as his builders destroyed 'the Dead Planet' has life similar to Venusians and thus may be beneficial for the mission and repairs. Arriving on Earth only under these conditions (when it's right next to Venus) suggests that Beta was avoiding Earth for reasons perhaps she only knows. When Beta and Gamma arrive they are both thrilled to have an oxygen atmosphere present and both set out to find a male to bring back to Venus. They meet a local and using a stunner and memory scanner learn of Earth from him while having a conversation between the stunning and scanning so as to keep him oblivious and themselves capable of responding as if from the planet. It's from him they learn they are on Earth, and they both agree that the man should be taken with them to Venus. After a day passes the two visit the man at his home where he lives with his younger brother. The man is curious as to if the women are single and even asks if they 'swing the other way'. The man flirts with Gamma and Beta watches amused only after the man kisses Gamma does Beta take it upon her self to steal a kiss bringing the man to her lips to which he reacts with shock telling Beta that 'such is to be given not taken'. Gamma stuns the man and angerly excuses Beta; and it's here that Beta's behavior as shown up until this point begins to differ. When Gamma returns Beta isn't at the ship, and that's when using a viewing screen Gamma witnesses Beta's act of murder and feeding all while begging Beta not to condemn herself and horrified contacting the Regent. Beta goes from close friend to trickster in the pursuit of self preservation and then having achieved that to dominion over the men of Earth. This shift was unexpected by viewers of the film, but seems to have started when she stole a kiss from the Earth man suggesting that such intimate contact awoke desires that had been dormant.