Samantha Morton (Fantastic Beasts and Where To Find Them) is joining Season 9 of The Walking Dead as a new series regular playing iconic villain Alpha, leader of the Whisperers.

Series creator and executive producer Robert Kirkman announced the casting Friday during the show’s panel at San Diego Comic-Con.

In the comics, the Whisperers are a mysterious group of survivors who disguise themselves with roamer skin to blend in and not get noticed, and in the series are formidable adversaries of Rick Grimes (Andrew Lincoln) and his allies. Morton’s casting confirms the Whisperers’ arrival in Season 9 and also puts to rest the much-speculated question of who would play Alpha in the series.

The Walking Dead returns for its ninth season on October 7 on AMC.

Morton was most recently seen on the big screen as Mary Lou in Fantastic Beasts and Where To Find Them, and also plays the role of Margaret Wells in Harlots, currently in its second season on Hulu. Oscar-nominated Morton’s other credits include Sweet and Lowdown, In America, The Messenger, and Her among others.