HBO has confirmed three of the most anticipated roles left to fill for Season 2 of its Harry Potter series, adapting Harry Potter and the Chamber of Secrets. Lenny Rush will play the house-elf Dobby, Billy Barratt will play the teenage Tom Riddle, and Bonnie Hill steps in as Ginny Weasley, taking over the role from Season 1’s Gracie Cochrane. All three characters carry serious weight in the second book, and the casting choices give a first real look at how the show intends to handle them.

Ginny Weasley: Bonnie Hill

Bonnie Hill inherits Ginny Weasley after Gracie Cochrane, who played the part in Season 1’s Philosopher’s Stone, chose not to continue with the show. Cochrane’s family said earlier this year that she was stepping away for personal reasons unrelated to the production, and HBO said at the time that it supported her decision and thanked her for her work on the first season. The search for her replacement was an open casting call for a UK-based actor in the same age range as the character, run through the show’s regular casting process.

The recasting lands at a pivotal moment for Ginny. Chamber of Secrets is the book where she stops being “Ron’s little sister” in the background and becomes a character in her own right, drawn into Tom Riddle’s diary and the events building toward the Chamber. Hill is stepping into a much bigger role than the character had in Season 1.

Tom Riddle: Billy Barratt

Billy Barratt, known for Invasion and Kraven the Hunter, becomes the first actor confirmed to play any version of Lord Voldemort in the HBO series, cast as the teenage Tom Riddle who appears through the diary in Chamber of Secrets. In keeping with the show’s pattern of casting younger than the films did for several adult and teenage characters, Barratt is close to the character’s book age of sixteen, whereas Christian Coulson was in his early twenties when he played the role in 2002.

Dobby: Lenny Rush

Lenny Rush, known for Am I Being Unreasonable? and Slow Horses, takes on Dobby, the house-elf whose warnings set off much of the plot in Chamber of Secrets. It’s a notable departure from the films, where Dobby was a fully CGI character voiced by Toby Jones. HBO has not said whether Rush will appear through prosthetics, motion capture, voice acting, or another approach, leaving one of the season’s most-watched creative decisions still unconfirmed.

Season 2, briefly

Season 2 adapts Chamber of Secrets and is currently moving through production at Leavesden Studios outside London, with several cast members confirming they were back on set in August, ahead of the fall start originally announced. Kit Harington was previously announced as Gilderoy Lockhart. The returning core cast includes Dominic McLaughlin as Harry, Arabella Stanton as Hermione, and Alastair Stout as Ron, alongside John Lithgow, Janet McTeer, Paapa Essiedu, and Nick Frost as Dumbledore, McGonagall, Snape, and Hagrid.

Francesca Gardiner writes and executive produces the series, with Mark Mylod directing multiple episodes. J.K. Rowling, Neil Blair, and Ruth Kenley-Letts of Brontë Film and TV, and David Heyman of Heyday Films, also executive produce. Season 1, Harry Potter and the Philosopher’s Stone, has wrapped filming and premieres on HBO on December 25.