I've managed to answer the other 49 questions and am now left with one irritatingly elusive one which has got me stumped. The theme of the quiz is Pantomime. Any help will be very gratefully received. The clue is:
Thank you so much, Trojanfarce. I'll be able to sleep at night again now! I tried anagrams and got nowhere - but then I've never heard of that character. Well done, and again, many thanks.