David Threlfall is joining HBO's highly anticipated Harry Potter television reboot as the voice of the Sorting Hat, alongside four newly announced cast members bringing some of Hogwarts' most recognizable supernatural residents to life.

The British actor, 73, best known for playing Frank Gallagher in Shameless, will voice the magical hat responsible for assigning students to their Hogwarts houses.

The series, based on J.K. Rowling's bestselling novels, is scheduled to premiere on HBO and HBO Max on December 25, with its first season adapting Harry Potter and the Philosopher's Stone.

According to a new casting announcement, Leo Bill, 46, will portray Nearly Headless Nick, the ghost associated with Gryffindor House, while Andrew Brooke will play the Bloody Baron, the resident spirit of Slytherin.

Daniel Fearn has been cast as the Fat Friar, Hufflepuff's ghost, with Laura Smyth taking the role of the Fat Lady, whose enchanted portrait guards the entrance to Gryffindor's common room.

Threlfall's casting brings another familiar British television performer into the production, following his acclaimed portrayal of the chaotic Gallagher family patriarch in Shameless and his appearance in the thriller Nightsleeper.

Bill previously appeared in Alice in Wonderland and The Living and the Dead, while Brooke's credits include PhoneShop and The Agency.

Fearn has appeared in Slow Horses and Things You Should Have Done, while Smyth is known for her work in Netflix's Baby Reindeer.

The new actors join an extensive ensemble led by Dominic McLaughlin as Harry Potter, Arabella Stanton as Hermione Granger and Alastair Stout as Ron Weasley.

John Lithgow, 81, will portray Hogwarts headmaster Albus Dumbledore, with Janet McTeer, 65, playing Minerva McGonagall and Paapa Essiedu, 36, taking the role of Severus Snape.

Nick Frost, 54, will appear as Rubeus Hagrid, while Warwick Davis, 56, returns to the wizarding franchise as Professor Filius Flitwick.

Other cast members include Lox Pratt as Draco Malfoy, Rory Wilmot as Neville Longbottom, Johnny Flynn, 43, as Lucius Malfoy and Katherine Parkinson, 48, as Molly Weasley.

The production has also announced casting for its second season, which will adapt Harry Potter and the Chamber of Secrets.

Kit Harington, 39, known for portraying Jon Snow in Game of Thrones, is set to play Gilderoy Lockhart, while Lenny Rush, 17, will portray Dobby.

Billy Barratt, 19, has been cast as Tom Riddle, with Rafe Spall, 43, appearing as Arthur Weasley.

Francesca Gardiner serves as writer and executive producer, while Mark Mylod directs multiple episodes.

Rowling, 61, is also an executive producer alongside Neil Blair, Ruth Kenley-Letts, David Heyman, Laura Neal and Jon Brown.

The series is produced in association with Brontë Film and TV and Warner Bros. Television.