Julian Fellowes Creator, Executive Producer, Writer Christine Baranski Agnes van Rhijn Actor Cynthia Nixon Ada Brook Actor Carrie Coon Bertha Russell Actor Morgan Spector George Russell Actor Denée Benton Peggy Scott Actor Louisa Jacobson Marian Brook Actor Taissa Farmiga Gladys Russell Actor Blake Ritson Oscar van Rhijn Actor Simon Jones Bannister Actor Harry Richardson Larry Russell Actor Jack Gilpin Church Actor Ben Ahlers Jack Trotter Actor Mike Cerveris Mr. Watson Actor Celia Keenan-Bolger Mrs. Bruce Actor Debra Monk Mrs. Armstrong Actor Donna Murphy Caroline Schermerhorn Astor Actor Kristine Nielsen Mrs. Bauer Actor Kelli O'Hara Aurora Fane Actor Patrick Page Richard Clay Actor Taylor Richardson Bridget Actor Douglas Sills Monsieur Baudin Actor John Douglas Thompson Arthur Scott Actor Erin Wilhelmi Adelheid Weber Actor Kelley Curran Mrs. Enid Winterton Actor Sullivan Jones T. Thomas Fortune Actor Gareth Neame Executive Producer, Director Michael Engler Executive Producer David Crockett Executive Producer Salli Richardson-Whitfield Director, Executive Producer Sonja Warfield Writer