Ferris, Jonathan, also known as Dr. Marconi: He is currently employed by the World Health Organisation (WHO) and has even picked up Robert Langdon from Harvard University. In the book we meet him for the first time in Piazza della Signoria wearing Plume Paris glasses and a golden earring, and displaying a rash, apparently caused by the Italian soap. The rash worsens, and his finger nails become bloody. Elisabeth Sinskey is sitting in a car near the square and seems to recognize the man even though she has been given sedatives. The man follows Langdon and Sienna as they escape from Palazzo Vecchio. He offers the docent outside the Baptistery 500$ to let him in for 5 minutes. He tells Langdon and Sienna that he is employed by the WHO. He gets a call from the Provost when he, Langdon and Sienna are on their way to Venice. He has apparently been the Provost’s contact in Florence. During the call it occurs to Ferris that his friends have become his enemies. It turns out that he is not employed by the WHO but instead works for the Provost. Earlier that day he has been dressed as Dr. Marconi. The beard and eyebrows were what gave him the rash. He follows Langdon and Sienna and helps them reach Venice. Sienna hits him hard in the chest in St. Mark’s Basilica to cause him to have trouble breathing.
Sienna knows from keeping an eye on him that he is not who he claims to be.
Gypsy woman: She sells masks in St. Mark´s Square and tries to sell to Langdon. She helps Sienna escape St. Mark´s crypt by holding out her arm after Sienna is propped up by Langdon.
Kier, Deb: Employee at NetJet U.S., a private jet company. She is contacted by Jonas Faulkman, who orders a plane for Robert Langdon. When Deb Kier enters the number from Langdon´s passport, she receives an alert and calls the authorities.
Knowlton, Laurence: He is a senior facilitator employed by the Provost. His task is to release the movie that Zobrist had asked the company to make. He asks the Provost to watch the movie and is rejected at first. But later, when the Provost starts to doubt whether to follow the protocols of the company, he watches the movie and realizes that he has been helping a criminal.
Langdon, Robert: He is a professor at Harvard University in Boston and is the main character of the book. Please see the article dedicated to him: https://www.florenceinferno.com/robert-langdon/
Mirsat: A guide at Hagia Sophia and a big fan of Robert Langdon.
Pimponi, Maurizio: Chauffeur of a water limousine in Venice. He takes Langdon, Ferris, and Sienna from the station to St. Mark´s Square.
Portinari, Beatrice: She was the love of Dante’s life. However, Beatrice married someone else, and Dante had to live without his beloved Florence and Beatrice. His love for Beatrice is a central theme in The Divine Comedy.
Russo, Ernesto: He is a guard at the Pitti Palace who watches over the only secret exit from the Boboli Gardens, which is through a grey door. He is an overweight 29 year old man who always dreamed about playing European football but now has to be satisfied with working a boring job as a guard in a place that nobody besides lost tourists ever visits. Langdon and Sienna are able to pry the code to the secret door out of him.