When I was younger I watched all the old reruns on TV Land. There was a black and white episode about a robot/alien that was friends with a little girl. He was taking lots of blood from her every time she visited, in a spherical ball like glass container.
Eventually the father/mother finds out what is going on and kills the alien/robot/monster, but comes to find out he was taking blood to save the human race and just doomed everyone.
Minus the part about the alien taking blood, this sounds a bit like the Twilight Zone episode "The Gift" (1962). In it, it's a boy, not a girl that befriends an alien. People from the boy's village kill the alien, only to find out that he was on Earth to
deliver a cure for cancer.
Monsters - "Glim Glim" (season 1 ep 13).
Glim-Glim is always jibber-jabbering high-pitched sounds, but sometimes we hear it translated in an eloquent narrator voice. He sits in the library going through books to learn more about humans, trying to figure out how to communicate with the kid for help in stopping a virus from destroying the human race, and talking about it into a glowing cube. “Must find another way.”
The girl watches him through a vent, holds his tentacle, becomes his pal. She learns to communicate with him and tries to help him in his mission to convince the adults that he’s “a friend.” They don’t trust him at all and the tough guy says shit like “A great hunter aaaaalways needs to know his prey” while gripping a very small wrench that I’m not convinced would even count as a weapon if he hit Glim-Glim with it. To be fair, their fear of Glim-Glim is not strictly xenophobia. It’s also because they keep finding severed heads and shit laying around. (I didn’t really understand that. The episode acts like Glim-Glim is just misunderstood, but apparently he’s ripping heads off like a Predator?)
They lose their shit when they see the alien (consensually) taking a blood sample from the girl using weird alien equipment. The ironic ending is that the dad shoots Glim-Glim, thinking he did something to the daughter, but then he finds her in the other room enjoying a Christmas tree that Glim-Glim made to prove to them that he’s a nice fellow. They forgot it was Christmas Eve!
The girl is excited to tell her dad about the tree, but after a minute remembers that there were just fucking gun shots in the other room, maybe she should find out what that was all about.
"Daddy? Where's my friend Glim-Glim? Daddy? Please tell me you didn't hurt him. Daddy, you didn’t hurt my friend Glim-Glim did you?"
