The announcement was made this afternoon at New York Comic Con by Marvel Head of Television Jeph Loeb.
They'll be joined by new additions Wynn Everett ("The Newsroom"), Lotte Verbeek ("The Fault in Our Stars"), Currie Graham ("Pompeii") and Reggie Austin ("Devious Maids").
In the second season, Peggy Carter (Hayley Atwell) journeys from New York City to Los Angeles for her most dangerous assignment yet.
Everett will play actress and inventor Whitney Frost, better known as the Marvel Comics supervillain Madame Masque, while Verbeek will portray Ana Jarvis, the free-spirited wife of Edwin Jarvis (James D'Arcy), who befriends Peggy, and helps her adjust to life in Los Angeles.
Graham has been cast as high-powered businessman (and Whitney's husband) Calvin Chadwick, with Austin play Jason Wilkes, a charismatic scientist who charms Peggy.