Professor is the real genius mind behind the money heist in The Spanish Royal Mint. He had started planning of this robbery few years back.
In fact, the plan was of Professor's father but execute by Professor. Professor real name in Money Heist is Sergio Marquina and Inspector Raquel know him by Salva.
Professor character played by Alvaro Morte. He is the favorite character of mine in this web series. Meticulous planning and execution by Professor character really admirable.