Help with tracking down the name of an old sci fi movie

[quixoticdreamer]

My dad is looking for the name of an old movie, he thinks it was made 1950-1960s, about an alien onboard a craft with humans who are trying to get back to earth and they keep moving further up into the ship/onto different levels to get away from the alien but it keeps persuing them, think in the end the alien gets killed and they make it back to earth but that's all he seems to remember from it so I apologise that it's quite vague, this is just a shot in the dark..