Netflix's Riverdale companion Sabrina has cast its Aunt Zelda.

Lord of the Rings and Homeland alum Miranda Otto has joined the cast of the untitled Sabrina the Teenage Witch drama.

Picked up with a two-season, straight-to-series order, the project reimagines the origin and adventures of the comic book character Sabrina the Teenage Witch as a dark coming-of-age tale that traffics in horror, the occult and witchcraft. It is described as in the vein of Rosemary's Baby and The Exorcist, and finds Sabrina Spellman (Mad Men's Kiernan Shipka) wrestling to reconcile her dual nature as a half-witch, half-mortal while fighting the evil forces that threaten her, her family and the daylight world humans inhabit. She is an empowered young woman who is just beginning her dark education as a sorceress, even as she tries to maintain a normal life as a sophomore at Baxter High. Intelligent, compassionate and brave to the point of recklessness, Sabrina is all that stands between us and the forces of darkness that threaten our world.

Otto will take on the role of Zelda Spellman, Sabrina's stern witch aunt. Proud and devout, Zelda believes there is no greater honor than serving the Dark Lord as a member of the Church of Night. She is the family’s disciplinarian, fiercely protective of Sabrina, and very much Cain to Hilda’s Abel. Lucy Davis was previously announced to take on the role of Aunt Hilda. Otto takes on a role previously played by Beth Broderick in the original Sabrina, the Teenage Witch.

Otto recently wrapped a one-season run on Fox's 24 revival and counts Showtime's Homeland and Fox's Rake among her small-screen credits. She also played Eowyn in the Lord of the Rings film franchise. Otto is repped by Gersh and Management 360.

Riverdale showrunner Roberto Aguirre-Sacasa, who also serves as chief creative officer of Archie Comics, penned the script for the series. Aguirre-Sacasa will direct the drama and executive produce alongside Riverdale collaborators Greg Berlanti, Sarah Schechter, Archie Comics CEO Jon Goldwater and Lee Toland Krieger. The project hails from Warner Bros. Television-based Berlanti Productions.

Otto joins a cast that also includes Shipka, Michelle Gomez (Doctor Who), newcomer Chance Perdomo and Jaz Sinclair (Easy, The Vampire Diaries).