Kit Harington has been tapped to join the highly anticipated Harry Potter TV series as the wizarding world’s celebrity-turned-Hogwarts instructor Gilderoy Lockhart, HBO confirmed to the BBC.

Harington is replacing actor Nicholas Hoult who could not film season two of the series due to a scheduling conflict.

Best known for playing Jon Snow for eight seasons in the award-winning series Game of Thrones, Harington also appears in the BBC and HBO financial drama Industry. The casting marks the English actor’s third collaboration with the American network and streamer.

Harry Potter and the Philosopher’s Stone is due to premiere on Christmas this year on HBO Max.

Season two will adapt the second book in the series by JK Rowling, The Chamber of Secrets, which chronicle’s Potter’s second year at the magical school.

“Before we begin year two at Hogwarts, there has been a slight change due to schedule: Kit Harington will be stepping into the role of Gilderoy Lockhart,” a story post reads on the official Harry Potter Instagram account.

The new series adaptation of the best-selling books stars newcomer Dominic McLaughlin as the boy wizard, Alastair Stout as his best friend Ron Weasley and Arabella Stanton as the young witch Hermione Granger.

Oscar-nominated actor Jon Lithgow has been cast as Hogwarts headmaster Albus Dumbledore and Nick Frost as gamekeeper Rubeus Hagrid.

Emmy-award winning Harington, a lifelong fan of the books, already has some familiarity with his new role: The actor voiced Lockhart in Audible’s star-studded Harry Potter: The Full-Cast Audio Editions last year.

The show could reunite him with director and producer Mark Mylod, who worked on Game of Thrones and is directing some Harry Potter episodes. Mylod is an executive producer on the new series along with author JK Rowling.

Lockhart was portrayed in the Warner Bros Harry Potter films by Kenneth Branagh, and is a key character in Harry Potter and the Chamber of Secrets, the second book in Rowling’s best-selling franchise.

The vain wizard who authored several books on his purported encounters with dark creatures serves as Hogwarts’ latest professor for the defence against the dark arts and fancies himself a mentor to Harry in his second year.

Hoult, known for his roles in X-Men, Superman and Mad Max: Fury Road, was announced for the role earlier this month. But HBO reportedly had to let the Superman actor out of his deal due to his commitments to projects that conflicted with a change in the series’ production schedule, according to Deadline, which first reported Harington’s casting. HBO confirmed the reporting to the BBC.

Representatives for Harington and Hoult did not immediately respond to requests for comment.

The HBO series is expected to take 10 years to complete, as producers plan multiple seasons covering each of Rowling’s seven books, which the eight blockbuster films were originally based on.