Related Clues:

• Missing a few marbles
• Uncannily spooky
• Unsettlingly strange
• Kind of duck
• Like ''The Shining,'' e.g.
• Klingon, e.g.
• Sci-fi villain
• Unheard-of
• Noncitizen
• Really spooky
• Like all primes but one
• 42-Across, for one
• Visitor from afar
• Lacking a match
• 'Can you believe it?!'