What does it mean when you keep dreaming of a celebrity?

Depending on who the "someone" is in your dream, it could mean simply that you're thinking about that person a lot. But the question is too general for a definite interpretation. Dreaming of someone you love and admire is very different from dreaming of someone you find repulsive, or someone who is a celebrity or a historical person or a complete stranger. In any case, dreaming of someone does not mean that person was thinking of you. Your dreams originate only within your own mind.