Lord of the Rings cast pull off 20-year reunion surprise

Stephen Colbert and the Lord of the Rings stars rapped their way through the track #1 Trilly. Photo / YouTube

One rap to rule them all.

The Lord of the Rings cast reunited on The Late Show with Stephen Colbert in the most surprising way – with a special hip-hop tribute.

The talk show host introduced the segment by declaring his Rings superfan status and insisting the cast should have been given a proper reunion as they near the 20-year anniversary of the release of The Fellowship of the Ring.

"It was 20 years ago this Sunday that this movie kicked off my favourite film series of all time," Colbert told the audience.

" … If you ask me, there is no better film series. Lord of the Rings is without a doubt the greatest trilogy in movie history. I know I may have said that many times before, but I have never — not once — rapped it. Until now."

With the help of Late Show resident musician Jon Batiste, Colbert kicked off his #1 Trilly rap, before some of the trilogy's most famous cast members popped up to drop some hilarious rhymes of their own, including Elijah Wood, Sean Astin, Orlando Bloom, Billy Boyd, Dominic Monaghan, Viggo Mortensen and Andy Serkis (with a cameo by Pitch Perfect star Anna Kendrick).

But the most jaw-dropping moment came when acclaimed actor Hugo Weaving – who played Elvish ruler Elrond in the fantasy franchise – joined in … and rapped entirely in Elvish.

Watch it for yourself:

Colbert has made his love of the fantasy franchise well-known in the past – so much so, that he was given a cameo in the 2013 LOTR prequel film, The Hobbit: The Desolation of Smaug.

He also took a joking swipe at the Harry Potter franchise, which is being given the full reunion treatment with Harry Potter 20th Anniversary: Return to Hogwarts premiering on Binge New Year's Day.

"Harry Potter's fine, but it's no Lord of the Rings. I mean, Dumbledore couldn't take a Balrog! Dumbledore was killed by a high school chemistry teacher!" he joked, referencing Professor Snape.