One of the biggest nostalgic waves that the new 'Fantastic Beasts and the Crimes of Grindelwald' trailer dropped on Potterheads was the brief stinger at the end where Dan Fogler's Kowalski meets a wizened, ancient figure who introduces himself as Nicolas Flamel, shocking audiences everywhere.
Played by Brontis Jodorowsky, the character has only ever been mentioned by name once in the entirety of the franchise, leaving most of his involvement in the story shrouded in mystery. It is based on a real-life figure of the same name, a famed French scribe and manuscript-seller in 14th century France.
Following the real-life Flamel's death, his books were sold under a marketing campaign that claimed he'd discovered the secrets of immortality and other universal mysteries. The claims grew so outrageous that readers eventually came under the impression that Flamel was a legendary figure, a mythic part of folklore as opposed to someone who actually existed.

From there, his legend propagated through fictional works. Because of this, Flamel's name has become synonymous with alchemy, the pseudo-science of transmutation, and the philosopher's stone, a fictional artifact which can perform incredible magical feats and grant its user immortality.
J.K. Rowling imagined these myths to be true in her Wizarding World. According to supplementary information on the Pottermore site, Flamel and his future wife Perenelle (also a real-life figure of renown) attended the French
