I watched this English movie or TV show during 1980s in my childhood. The story was in a spaceship. Several people was in the spaceship, among whom the main character was a lady.
The villain appears as electric sparks near the ceiling of a room in the ship. He appears only when a lady remains alone. He then converts to a man in long black robe. He tries to penetrate his metallic long fingernail into her neck. The lady was so scared and tried to escape. One day he was successful to penetrate. Then her mind was converted and inclined to him. Then he took her away with a small space shuttle detached from the main spaceship.
He was driving the shuttle but suddenly he started to be melted down and finally destroyed. Then the lady went back to the main spaceship and met her friends.