A casting breakdown reveals the actress is playing a character named Samantha, a mother and bohemian artist described as, "an attractive, strong, smart, charming and articulate woman with a vulnerable side." However, AMC sources indicate the character's name and description may likely just be a "placeholder." There is no character named Samantha in Robert Kirkman's original comic books, or the numerous video games. It isn't known exactly when this character will first appear, but Alexandra Breckenridge will have the option to become a series regular in Season 6.
The Walking Dead currently has 17 actors listed as series regulars, the most in the show's history, with a few new characters appearing in the coming weeks. Seth Gilliam's Father Gabriel Stokes, who was featured in a trailer from earlier this week, will debut in this week's episode, "Strangers", airing October 19, and the show also added Tyler James Williams as Noah last month, another character who isn't featured in the original comics. The Season 5 premiere also featured the surprise addition of Lennie James' Morgan, who starred in the Pilot episode back in 2010, and the Season 3 episode, Clear.
The show is also holding casting sessions for another new addition, "Donna," described as an influential and respected journalist who is also a mother with a "wise-ass" sense of humor. There were reports that Kate Burton (Scandal, Grey's Anatomy) is up for the role, although AMC reps claim that isn't true.
Alexandra Breckenridge played Young Moira in the first season of American Horror Story, and also appeared as Kaylee in the third season. She has also voiced a number of different characters on Fox's Family Guy.