The show’s official Twitter feed has announced that he will appear as a character named Tyr Seward.
Bradley plays the role of Samwell Tarly in Game of Thrones and has also starred in TV series Borgia.
British actor James Fox, uncle of Silent Witness star Emilia Fox, will also reportedly be playing a character called King Rodor in the new series.
It was confirmed last week that Merlin cast members Colin Morgan and co-star Katie McGrath will both lead a panel at next month’s Comic-Con, which will include an exclusive sneak preview of Series 5 and a specially-created blooper reel.
Are you looking forward to Series 5? Let us know below…
> Order the Series 4 Volume 1 DVD on Amazon.
Watch a clip from Series 4…