6. The Priory of Sion
This secret society is actually a hoax! It was created long ago, in 1956 by Pierre Plantard who plotted with de Cherisey and de Sède and tried to keep the charade going for a long time. Nonetheless, with the Da Vinci Code written by Dan Brown, people were intrigued by this Priory of Sion.
Even the authors of a book called The Holy Blood and the Holy Grail were fooled by this hoax, stating that the group dated from AD 1099 and it had as Grand Masters the famous Isaac Newton and Leonardo da Vinci.