HBO has released the first trailer for Harry Potter 20th Anniversary: Return To Hogwarts.

• READ MORE: Harry Potter & The Cursed Movie: how Fantastic Beasts: The Crimes Of Grindelwald became JK Rowling’s most controversial film

The special, set to be released on New Year’s Day, reunites Daniel Radcliffe, Rupert Grint, Emma Watson and other cast members to celebrate the 20th anniversary of the franchise’s first film, Harry Potter And The Philosopher’s Stone.

Other cast members featured include Robbie Coltrane, Helena Bonham Carter, Ralph Fiennes, Jason Isaacs, Gary Oldman, Imelda Staunton, Tom Felton, James Phelps, Oliver Phelps, Mark Williams, Bonnie Wright, Toby Jones, Alfred Enoch, Matthew Lewis, Evanna Lynch, Helena Bonham Carter and Ian Hart.

Directors across all eight films will also make appearances, including Chris Columbus, Alfonso Cuarón, Mike Newell and David Yates, alongside producer David Heyman.

Speaking in the trailer, Radcliffe says: “The thing that scared me the most was the implication that the most meaningful thing in our life was done. And there’s something so joyous about seeing everyone, and being like ‘it wasn’t though’.”

He adds: “I wouldn’t be the person I am without so many people here.”

The main notable absence is author JK Rowling, who has been criticised in recent years over allegations of transphobia.

Speaking about the special, president of Warner Bros. Global Kids, Young Adults and Classics, Tom Ascheim, said: “It has been an incredible journey since the debut of the Harry Potter And The Philosopher’s Stone film, and witnessing how it has evolved into this remarkable interconnected universe has been magical to say the least.

“This retrospective is a tribute to everyone whose lives were touched by this cultural phenomenon – from the talented cast and crew who poured their heart and soul into this extraordinary film franchise to the passionate fans who continue to keep the Wizarding World spirit alive 20 years later.”

The Harry Potter franchise spans seven mainline books which were adapted into eight films, culminating in 2011’s Harry Potter And The Deathly Hallows Part 2. There’s been two spin-off films in the Fantastic Beasts series, with a third set to be released April 15, 2022.

In 2016, a theatre adaptation titled Harry Potter And The Cursed Child was released which continued the story from the original books.

Harry Potter 20th Anniversary: Return To Hogwarts will be released January 1, 2022 on HBO Max in the US and NOW in the UK.