Christine Baranski as Agnes van Rhijn - Agnes is a proud and stubborn aristocrat who will never accept that the world has changed, and that ancient values are being replaced by new ones. She found herself penniless as her parents’ fortune was foundering, but she managed to catch a husband just in time. Now a widow, Agnes still has her son Oscar, whom she worships, but her worship is not returned.
Cynthia Nixon as Ada Brook - Unlike her sister Agnes, Ada never found a husband and was forced to rely on her sister’s charity. She is not naturally confrontational, but she is capable of standing up for what she believes.
Carrie Coon as Bertha Russell - Bertha comes from the ordinary middle-class. She backed her instincts when she set out to catch her husband George, the son of a merchant family who has proved to be a financial genius. She is determined to use her money and position to break into a society that resists change at every turn.
Morgan Spector as George Russell - A classic robber baron of his own time, Russell is pleasant enough in company. He’s fond of his wife and his children, but utterly ruthless in business. He has already acquired millions and many more will follow. In every challenge, George must win.
Denée Benton as Peggy Scott - Is a young, ambitious, writer. She was raised in New York and educated at the prestigious Institute for Colored Youth in Philadelphia. We meet Peggy at a crossroads. She’s haunted by her past and lingering questions that’s she unable to find answers to, so she chooses to leave Pennsylvania and return home. When she meets Marian both women are seeking a fresh start, and form an unlikely friendship as they begin this next chapter of their lives in New York. But Peggy’s secret will eventually be revealed, causing a tectonic shift in her world.
Louisa Jacobson as Marian Brook - Our principal heroine. Lovely and strong. Born to an old Pennsylvania family, but her father has left her without a penny. In one way, Marian knows that her probable fate will be to marry as well as she can and survive, but she wants more than this. She is curtailed by the rules of her time, but there is a modern streak in her, too. She wants to do something with her life. She wants to be fulfilled. She moves from Doylestown to New York City after her father dies to live with her estranged aunts, Agnes van Rhijn and Ada Brook.
Taissa Farmiga as Gladys Russell - A classic, innocent and lovely child of the rich who doesn't want a governess or for her mother to treat her as a child anymore—she yearns to be out in society meeting suitable young men. She doesn’t really know how her father made his money, and she doesn’t much care, but she is used to it and wouldn’t know what to do without it. She has an independent streak, but her defiance is no match for her mama. Her mother uses her as a tool for her own ambition and forces her toward socially advantageous situations.
Blake Ritson as Oscar Van Rhijn - Agnes van Rhijn's charismatic son. He's decided it's time to settle down and has become obsessed with money while on the lookout for a serious heiress who will allow him to live, as he would put it, properly. Smart, attractive, poised, charming and mischievous, he enjoys witty banter. He is one of the few who will stand up to his mother and will not listen to his mother’s advice which will cause her a good deal of frustration.
Simon Jones as Bannister - An English immigrant the van Rhijn’s butler joined the household a year before the death of Mr van Rhijn and so, for the old lady, he is a link with her own past. He likes to give the impression that he is immensely grand, and keeps a watchful eye over the rest of the staff.
Harry Richardson as Larry Russell - Appealing and good natured with an easy charm, Larry is a recent Harvard university graduate eager to make his way in the world. Above all, Larry is his mother's child, her Achilles' heel, the one person she loves without limit and he loves her as well. He is protective of his little sister, Gladys, and like her he is a classic child of the rich. He thinks he doesn't care about money, because he has always had plenty of it.
Thomas Cocquerel as Tom Raikes - Tom is a sensible young lawyer from Doylestown, PA. He’s been a solitary and career-driven practical man but is smitten when he meets Marian, his late client’s orphaned daughter. He relocates to New York City in pursuit of a relationship with Marian. Tom understands that Marian’s aunts are very conservative and he’s careful not to overstep any boundaries along the way. He’ll put up a fight to get what he wants, but he’s an appealing, charming gentleman above all else.
Jack Gilpin as Church - Church is the Russell family’s butler. He is American, from a dismal background, but evades his past by excelling at his job. He has no time for nonsense in the workplace due to his attention and care for his job. Above all, he’s Bertha’s ally and he intends to stay reasonably true to her every step of the way, unlike her own maid.
Jeanne Tripplehorn as Sylvia Chamberlain - Mrs. Chamberlain is a tall and beautiful enigmatic figure. She’s a genuine expert in the creative arts and a great art collector, but is almost entirely excluded from high society because of her suspected past until Marian shows her kindness.
Audra McDonald as Dorothy Scott - Is a devoted wife, mother and accomplished pianist, but her life is unsettled because her family is in turmoil. She and her husband Arthur are estranged from their daughter Peggy. Dorothy’s fervent desire is to reunite with her only child and put the past behind them. However, she soon makes a shocking discovery that disrupts and jeopardizes any hope of family reconciliation.
Kelli O’Hara as Aurora Fane - Aurora Fane is Agnes van Rhijn’s niece by marriage and takes Marian under her wing when Marian makes her entrance into New York society. Aurora is naturally elegant, likeable, honest, loyal - but above all, Aurora is aware of the social game she must play to maintain her place amongst the upper class.
Donna Murphy as Mrs. Astor - Imperious and commanding, Mrs. Astor is the most prominent American socialite of the time. As the chief gatekeeper standing in the way of the Russell family's acceptance into New York society, Mrs. Astor’s approval is something that Bertha Russell is willing to achieve at any cost.
Michael Cerveris as Watson - George Russell’s valet is as steadfast as he is stoic. In private moments, a mysterious past and fall from grace is suggested. However, this does not dampen his optimism about the Russell family and their potential for success in New York society.
Debra Monk as Armstrong - As Mrs. van Rhijn’s maid, Armstrong enjoys an elevated position amongst the staff of the Brook House. Armstrong’s deep social biases, coupled with her need to be on the inside of every secret, promises to get her into trouble. Unfortunately, her private life is already fraught with trouble.
Katie Finneran as Anne Morris - Anne is the haughty and unforgiving wife of city alderman Patrick Morris. She’s established her place in this small circle of wealthy women and is determined to keep that circle closed to new money interlopers.
Celia Keenan-Bolger as Mrs. Bruce - As the Russell’s new housekeeper, Mrs. Bruce comes highly recommended – but not without something to prove. As a senior member of the house, she has been tasked with assisting Bertha with hosting social events worthy of New York’s elite.
Kristine Nielsen as Mrs. Bauer - A German immigrant, Mrs. Bauer has found her career as a cook for Mrs. Van Rhijn. Blessed with maternal instincts that stretch beyond the kitchen, she acts as a mother figure to the younger members of the Brook House staff, especially young Bridget.
John Douglas Thompson as Arthur Scott - Is a formerly enslaved man who left the south for a better life in New York. He studied to become a pharmacist and runs his own successful business. He’s a protective, stern, patriarch who is at odds with his daughter and her life choices. He, too, seeks family unity, but Peggy’s secret proves to be an insurmountable obstacle to that end.
Bill Irwin as Cornelius Eckhard - Though Ada hides it well, her interest is piqued when Cornelius reappears in her life after many years. A former beau from her days in Pennsylvania, Cornelius and Ada haven't seen each other since the Civil War threw all of their lives into chaos. Cornelius makes his interest in rekindling their friendship clear, and while Ada's niece Marian is thrilled at the idea of her aunt finding romance, Ada's sister Agnes remains dubious about his motives.
Patrick Page as Richard Clay - As George Russell’s loyal secretary, Clay is charged with running the railway tycoon’s booming business. Efficient and savvy, Clay is as quick with an intelligent solution as a sly workaround, and George uses the full extent of Clay’s unique skills in the pursuit of financial security.
Douglas Sills as Baudin - Monsieur Baudin is the stylish, particular, and sometimes hysterical chef of the Russell house. To Bertha, having a French chef is the height of chic, and his employment is considered a feather in her social cap.
Amy Forsyth as Caroline “Carrie” Astor - Carrie Astor is the handsome daughter of one of the most powerful women in New York City and her mother’s status often disrupts the ease with which Carrie would prefer to live her life as one of the most popular young women in town.
Taylor Richardson as Bridget - Bridget is a combined housemaid, kitchen maid, and lady’s maid in the Brook house. She’s a decent and hard-working immigrant girl from Ireland who has come to America to build a new future, though she has low expectations of life because of a troubled and abusive past.
Kelley Curran as Turner - Turner is Bertha’s ambitious American lady’s maid, who, though grudgingly accepting of her position in the Russell house, does not intend to be a servant all her days. Her loyalty is skin deep and she is always looking for a way out.
Ben Ahlers as Jack Treacher - Jack is a footman/hall boy/jack of all trades in the Brook house. A perfect footman in those days would be 5’10” or taller, as height was desirable, although Jack would not be considered the perfect anything. He does whatever jobs no one else wants to do and doesn’t complain.
Nathan Lane as Ward McAllister - 1827-1895, is chiefly remembered now as the inventor of the phrase, "the four hundred." This was the number of people who were worth bothering with in New York society. McAllister serves as Mrs. Astor’s right-hand man and his chief business and pleasure in life is help her guard the gates to High Society. He has a great deal to offer Bertha Russell in the way of opening doors if she can enlist his help. Luckily, he has a soft spot for wealth and ostentation, which she can supply in spades.
Sullivan Jones as T. Thomas Fortune - 1856-1928 He was born into slavery in Florida. As a child he witnessed the terror of the Ku Klux Klan that fueled his activism as an adult. He had some formal education at Howard University and practical education as a printer’s assistant. In the early 1880’s Fortune became an influential member of the Black intellectual community in New York as an activist, orator, journalist, writer, editor and publisher of The New York Globe and other papers. Through Fortune we are invited into the elite world of the Black press where he meets Peggy Scott. Fortune recognizes her talent and hires her to write for The Globe. Fortune is not averse to conflict, questioning authority and breaking the rules in both his personal and professional life.
Linda Emond as Clara Barton - 1821-1912 was a pioneering nurse, who founded the American Red Cross. She was a champion of women's education, as well. and, during the Civil War she was known as the "Florence Nightingale of America." She assisted the Grand Duchess of Baden in founding military hospitals during the Franco-Prussian War of 1870, when she became involved with the Red Cross, and she determined that there would be an American branch, opening her first local society in Dansville in 1881. She also became interested in women's suffrage, and racial equality, a comparatively new idea for her generation. Her name, on schools, on streets, on buildings, is to be found all over the United States.
Michel Gill as Patrick Morris - Husband of Anne Morris, Patrick is a banker and Alderman belonging to the established American/New York upper class. His wife is prominent in Society. When he and Charles Fane foolishly decide to take on George Russell, they are drawn into a poisonous web of their own making.
Ward Horton as Charles Fane - Husband of Aurora Fane, Charles is a banker and Alderman belonging to the established American/New York upper class. His wife is prominent in Society. When he and Patrick Morris foolishly decide to take on George Russell, they are drawn into a poisonous web of their own making.