X is mentioned as Claude Frollo’s scientific inspiration in Victor Hugo’s novel The Hunchback of Notre Dame.
He has been alleged to be the eighth Grand Master of the Priory of Sion.
His name has been mentioned in the pseudohistory book The Holy Blood and the Holy Grail, Umberto Eco’s novel Foucault’s Pendulum, and Dan Brown’s novel, The Da Vinci Code.
He is also a significant part of a Harry Potter book.
Identify X.