Recurring
Ramón García (Ramón García Monteagudo) as Cardinal Aguirre
Antonio Petrocelli as Monsignor Luigi Cavallo, Cardinal Voiello's right-hand man
Kiruna Stamell as the Abbess of the Monastery of Saint Therese, the head of the cloister nuns
Nora Waldstätten as Sister Lisette, a cloister nun whose mother is ill
Jessica Piccolo Valerani as Sister Pamela, a nun nursing comatose Pope Pius XIII in Venice
Kika Georgiou as the Woman in Red, the head of a constant vigil over comatose Pope Pius XIII in Venice
Nadie Kammallaweera as Sister Suree, a nun serving the pope in the Vatican
Unknown actor as Girolamo Matera, Voiello's best friend who has a severe disability
Massimo Cagnina as Don Mario, a priest who hosts Esther at his church
Eco Andriolo Ranzi as Sister Caterina, a young cloister nun who commits fornication with a refugee
Agnieszka Jania as Sister Ivanka, a young cloister nun
Zaki Bibawi Ayyad as Faisal, a refugee hiding in the Vatican Gardens who later commits fornication with Sister Caterina
Tomas Arana as Tomas Altbruck, Sofia's husband
Claudio Bigagli as Duilio Guicciardini, the Italian Minister of Economy and Finance
Janet Henfrey as the Duchess of Brannox, Sir John's mother
Tim Barlow as the Duke of Brannox, Sir John's father
Daria Baykalova as Amber, Bauer's girlfriend
Alessandro Riceci as Fabiano, Esther's love interest
Enea Barozzi as Attanasio, a young man with physical deformities
Lore Stefanek as Attanasio's mother and a wealthy lawyer
Alex Esola as Freddy Blakestone, a tennis player and Bernardo's lover
Ignazio Oliva as Father Valente, one of the Pope's assistants
Marcello Marziali as Don Mimmo, an old friend of Voiello's
Giancarlo Fares as Franco, Girolamo's caregiver
Daniel Vivian as Domen, the pope's butler
J. David Hinze as Leopold Essence
Yuliya Snigir as Ewa Novak, Helmer's wife
Charlie Potts and Joshua Smallwood as Adam Brannox, John's twin brother
Callum Potts and Matthew Smallwood as young John Brannox
Hella Stichlmair as young Duchess of Brannox, John's mother
Jonas Crodack as young Duke of Brannox, John's father
