Downton Abbey is probably the most popular period drama ever made. Its blend of likable characters, exquisite set design, and all-around grandeur is an infectious concoction for viewers looking for that old-world charm in their entertainment.

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But, for all its popularity, a lot of TV viewers might have forgotten how many big names in film and TV made appearances on the series. From the main characters to the supporting cast, there are a ton of actors who joined the ranks of the cast that many of us completely forgot. Here are the biggest names who made appearances on the British series.

Lilly James

While she might have been a mainstay for multiple seasons, fans might have forgotten that Lilly James was on the series. James has become quite the name thus far in entertainment, playing roles in Disney's Cinderella and Edgar Wright's Baby Driver.

James played the sweet and kind cousin to the Crawley family, Rose. Rose was a lighthearted youth who brought a ton of life back into the show after the death of Sybil, daughter of Robert and Cora. If it wasn't for her long-standing role on Downton Abbey, Lilly James might not have become as big a name as we know her to be today.

Charles Edwards

You might not know Charles Edwards by name exactly, but you'll recognize his face to be sure. This British actor has made appearances all over the place, in series both large and small. In Downton Abbey, Edwards played Michael Gregson, the fallen lover and late fiance to Lady Edith Crawley.

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Though he was in the series for a short time, his presence continued to be felt through his daughter Marigold. Edwards can be recognized for his work as well in series like The Crown. Here he can be found playing Martin Charteris, the Baron Charteris of Amisfield. Here he played the courtier to Queen Elizabeth.

Dan Stevens

Ok, perhaps you do remember Dan Stevens. Stevens played Matthew Crawley, heir to Robert and future lover and husband to Lady Mary Crawley. Sadly, Stevens didn't last nearly as long as he could have, leaving the show and being killed off in a car wreck.

Stevens has since gone on to some major projects. He has lead the FX X-Men series Legion, earning a ton of critical praise in the process. He also starred as the Beast in the remake of Disney's classic animated film Beauty & The Beast. Without leaving the show, he never would have been able to pursue these career highlights.

Penny Downie

Penny Downie is one of the most talented and recognized British actresses in the business. Apart from her film career, she has held a fantastic theater career as well. In fact, she was in the much-lauded production of Hamlet alongside David Tennant, playing his mother Gertrude.

But, she also held a brief role on Downton Abbey. Here she played mother to Rose's betrothed, Lady Sinderby. She played quite the foil to her husband, refusing to allow him to ruin the chances of Rose and her son. Her support allowed the two to marry without too many hiccups in the process.

Iain Glen

Iain Glen is known by many in the film and TV community for his roles in many science fiction, fantasy, and comic book series. He is probably best known for his role in Game of Thrones as Jorah Mormont. He can also be found in the DC Universe series Titans playing a matured and weathered Bruce Wayne.

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If you forgot though, he also played a suitor to Lady Mary in Downton Abbey. Glen played the role of Richard Carlisle, a mean spirited snob who nearly forced Lady Mary to marry him. Luckily, Mary refused and went for Matthew, leaving Carlisle in the dust.

James Faulkner

James Faulkner played none other than the husband to Penny Downie's character, embodying the role of Lord Sinderby. His disapproval of his son's partnership with Rose was one of the stinging points of his run, until Rose spared him the embarrassment of his infidelity coming to life.

Faulkner plays a great villain, especially in his other best-known role in Game of Thrones. The actor played Samwell Tarly's father Randyll Tarly. Leader of his house, Daenerys Targaryen burned him alive after defeating him and the Lannister forces in battle. Only time will tell what other villains Faulkner will play in his career.

Richard E. Grant

Richard E. Grant is one of the most recognizable British actors of his generation. He has played numerous roles in many films, including but not limited to Can You Ever Forgive Me, Bram Stoker's Dracula, and the upcoming conclusion to the Skywalker Saga Star Wars: The Rise of Skywalker.

In Downton, he played art collector and enthusiast Simon Bricker. After befriending Lady Cora while observing Downton's art collection, Bricker attempts to woo her. Throughout half a season, Bricker constantly flirts and tries to make moves on Cora, much to the distaste of Robert.

Paul Giamatti

Out of all the American actors who could have appeared in this series, few probably expected someone like Paul Giamatti. Giamatti is a beloved performer in the U.S. who has many, many film credits. Famous credits include Sideways, Big Fat Liar, the period drama John Adams, and American Splendor.

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In Downton, he played Cora's brother Harold Levinson. This American newcomer was quite the opposite of the hoity-toity behavior of his British counterparts. A no-nonsense man, Levinson was lost among the upper class of Europe. Luckily, without losing himself, he was able to make companions.

Rose Leslie

This Game of Thrones alum was the fictional and real-life love interest to her now husband, Kit Harington. Leslie played the wildling Ygrite, who fell in love with John Snow beyond the wall. Sadly, she was eventually murdered by the young Night's Watch member Olly.

Before all that though, she was nothing more than a simple maid in the Downton House. Eventually, she left her service, going after a new career as a typist. Eventually, come the final season, Leslie would return briefly for an episode, reminding us all that she used to be there.

Charlie Cox

That's right, Daredevil himself used to be a visitor to the halls of Downton Abbey. Before he was fighting crime in Hell's Kitchen, Charlie Cox was pretending to swoon the like of Lady Mary Crawley.

In reality, Cox's character, the snooty Philip Villiers, Duke of Crowborough, was a bit too busy making out with footman Thomas Barrow. The two shared a brief romance until Philip realized there was no money waiting for him in Downton by marrying Lady Mary. So, he took off, only appearing briefly in this first season.

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