Probably Voldemort.

All substitution ciphers are weak. When I was 10, I was on a camp where we “discovered” an encrypted page in a night game and the next day, a game of searching for scattered “clues” (substitution pairs) took place. In the meantime, I had deciphered the message using frequency analysis and guesswork so the pissed-off organizers created another page with the same cipher for our team to solve. I was grounded for “spoiling the fun” while others were playing, and our team came last because they had to wait for their page.