Curses, foiled. For the first time. 
How can we live in a world in which several different series of gentleman burglars aren’t the norm? (Others include The Saint, and The Toff, and supertypes like The Shadow and Batman were offshoots.) Don’t we want rich people to be ripped off by their weekend guests?
To atone, the weird history. Hornung created Raffles, with his subWasonian sidekick Bunny, in 1898. Yes, he was the one who married Doyle’s sister. They hung around together and he wanted to be a writer just like Artie, so much that he deliberately aped Holmes, turning him inside-out. He did three collections of short stories and a novel. A half dozen films were made and then he moved to television, but never got any popularity in the U.S. We don’t go for men named Bunny.
Leblanc came later, starting in 1905, but he was far more interesting and successful. The one to read is Arsene Lupin vs. Herlock Sholmes, a collection where Lupin battles the transparently renamed Holmes. So both have a direct Holmes connection, which is probably why my aging brain conflated, them. Lupin is mostly forgotten today, but you could make a good case that he was second only to Holmes in popularity. You know a character is instantly identifiable when parodies are written. Holmes parodies number in the hundreds. Lupin parodies go back to the early part of the 20th century and were probably second in number only to Holmes. He was later overtaken by hardboiled parodies but those are mostly generic rather than specifically about a character. And there are bunches of films from half a dozen countries.