Natalia Tena is one of the few actors on this list that had quite a significant role in both series. As a part of the Harry Potter cast, Tena played Nymphadora Tonks, a witch and Metamorphomagus, able to change her appearance at will. She was an important ally to Harry Potter and one of the heroes of the Battle of Hogwarts. In Game of Thrones, the actress had a less magical but still important role of Osha, a wildling and a protector to the Stark children, especially Rickon Stark.

The caretaker of Hogwarts, Argus Filch, joined the Game Of Thrones cast in 2010 when he was cast as Lord Walder Frey. The British actor is best known for his roles in the "Harry Potter" series "Game Of Thrones" and is also known for playing a supporting role in "King Lear" for which the actor was awarded the "Laurence Olivier Award". While speaking about his "Game Of Thrones" character, he said that he would not mind seeing Walder die in a painful way.

Michelle Fairley's performance as Catelyn Stark in "Game of Thrones" is, perhaps, her most memorable time on screen. She truly sunk her teeth into the role making it her own, especially during the gruesome scenes of the Red Wedding. It is not a widely known fact but Fairley also appeared in "Harry Potter and the Deathly Hallows: Part 1" where she played Hermione's mother. Albeit a much smaller role consisting of a single scene in the entire film, Fairley can still proudly say that she's been a part of two giant cultural phenomena.

Clearly, if you are not a die-hard fan, you won't remember Ian's presence in the "Harry Potter" films. However, his role might shock you as he played Olympe Maxime... well, not played but was used for full-body shots in order to make the character bigger. Throughout "Game Of Thrones", Ian played a lot of roles. He played a White Walker (season 1-2), Gregor Clegane (season 2), Dongo The Giant (season 3-4), Wun Wun (season 5-6) and Giant (season 8). As you can see, this Game of Thrones actor has been enjoying quite some roles in this world and the fans will clearly remember him in the future. His latest project was in 2017 in the big blockbuster, "Star Wars: The Last Jedi" in which he played Bollie Prindel. Clearly, the actor loves to be a part of the fantasy world.

Many remember Jim Broadbent as the enigmatic Potions Master at Hogwarts School of Witchcraft and Wizardry, Horace Slughorn, who appeared in the final 3 movies of the "Harry Potter" series. It is quite fitting that Broadbent then transferred to "Game of Thrones", only to play another man of science. In the Westerosi world, Broadbent portrayed Archmaester Ebrose in Season 7.

The voice of Acromantula in the "Harry Potter" series, if you did not know that, that's a fun trivia fact for you today. This Harry Potter actor has been in the acting business since the '50s and his career is still going strong. In "Game Of Thrones", the actor portrayed the role of Pycelle, the grand master of multiple kings. He appeared in a whopping 31 episodes of the show, the last season for the actor was the 6th season in which he was stabbed to death by Qyburn's little birds. Currently, the actor is working on the film "The Toll" which is set to come out in the near future.

Ciarán Hinds is an Irish actor with an impressive list of roles under his belt so it's no wonder that he was part of "Thrones" and "Harry Potter". In the magical world, Hinds played Professor Dumbledore's brother, Aberforth Dumbledore, who was instrumental in Harry Potter's resistance against Lord Voldemort. It's a funny coincidence that in "Game of Thrones", Hinds' character also led a resistance against the Night's Watch. Mance Rayder was the leader of the Free Folk and "King-Beyond-the-Wall".

Freddie Stroma is an English actor and model who played Cormac McLaggen in the final 3 films of the "Harry Potter" series. The aggressive and self-assured Gryffindor seventh year proved a useful ally to Harry Potter when he took part in the Battle of Hogwarts. In "Game of Thrones", Stroma played a minor (and less heroic) role of Samwell Tarly's younger brother, Dickon. Due to scheduling conflicts, the role was later recast and Tom Hopper took over.

Amycus Carrow, the mighty death eater in the "Harry Potter" series, was also a part of the "Game Of Thrones" family. He played Dagmer Cleftjaw, the ironborn reaver in House Greyjoy service. His "Game Of Thrones" stint lasted for 5 episodes. Currently, the actor is still working in the film industry and fun fact, in 2015, he and his "Game Of Thrones" co-star Kate Dickie starred in the critically acclaimed horror film "The Witch".

Pike, or better known as the member of Draco Molfoy Slytherin's boy gang, was also a part of the "Game Of Thrones" family. Bronson played the role of Will, however, the role was short lived as he was soon captured and executed by Ned Stark. Bronson Webb's latest film-related work was the 2015 film "Victor Frankenstein". However, the film was panned by critics and failed at the box office.

Irma Pince was one wicked librarian witch that all of the students loathed. Surprisingly, she was also in "Game Of Thrones". However, you might have missed her because she played a very small role of a Bravoosi woman in the sixth season. Currently, the British actress' latest work was a guest role in the episode of British TV show, "Doctors".

Skinny ministry wizard, that is the only way people describe Daniel Tuite while regarding his role in "Harry Potter". His "Game Of Thrones" journey also came like a surprise to the actor, mainly because the role of Lothar Frey was first played by another actor, Tom Brooke. However, Tom Brooke was recast in season six and the honor of playing Lothar was given to Daniel Tuite. Daniel is still acting and currently has two films in development: "The Show" and "Carmilla".

An old ministry employee with big glasses was the role that British actor Nicholas Blane portrayed in the "Harry Potter and The Order Of Pheonix" movie. His role was like a little cameo but die-hard "Harry Potter" fans still remember him. In "Game Of Thrones", however, the actor got a bit more to work with as he played the Spice King. He starred in 3 episodes in season 2 and eventually was killed by Pyat Pree during the meeting with Daenerys. Currently, the actor has one project on the horizon called "Hope Gap" that is set to hit theaters in 2019.

Mr Borgin, a wizard and a book shop owner, which you might not remember from the "Harry Potter" film series 'cause he was only included in the deleted scenes of "Harry Potter and The Chamber Of Secrets" DVD. You could also just blink and miss him in "Game Of Thrones" 'cause he mainly played a small role of a protester in the second season of the show. Currently, the British actor isn't very active in the film industry, however, he has a project in development called "Schadenfreunde"