"We seek him here, we seek him there, those Frenchies seek him everywhere. Is he in heaven or is he in hell? That damned elusive Pimpernel."
I know this book primarily from an early 80s English adaptation starring Anthony Andrews, Jane Seymour, and, in one of his earliest roles, Ian McKellen. I always thought the book was French but Barones Orczy was actually a Hungarian-born English author. This began life as a very successful play and then turned into a series of novels. It's a potboiler and so entertaining, but a little silly and its pro-royals sentiments are off-putting to this American reader. Filmed multiple times. Not sure if he or Zorro came first, but they were among the first to have alter egos. Be sure not to accidentally pick up the blaxploitation take-off "The Scarlet Pimp."