Who Is Olivia On 'This Is Us'? Janet Montgomery Has An Impressive Acting Career Of Her Own

This Is Us is arguably one of the best new series of the television season. Since it's debut, viewers have fallen in love with siblings Kate (Chrissy Metz), Randall (Sterling K. Brown), and Kevin (Justin Hartley), not to mention their charming parents Rebecca (Mandy Moore) and Jack (Milo Ventimiglia). As we learn more about the lives of the Pearson family, we're introduced to new characters and new faces. Recently, Kevin moved to New York for a change of pace after leaving The Manny, the show he'd become known for. Like many actors looking for a new gig, he decided to try his hand at Broadway and despite a terrible audition with his co-star Olivia, played on This Is Us by Janet Montgomery, he got the role.

For those of you who are already fans of Olivia's character, I have good news: she's not going anywhere. Creator Dan Fogelman told Entertainment Weekly, "Olivia becomes a really big part of his story. She’s both the most appealing and the scariest woman to possibly enter someone’s life in Kevin’s position right now, so there’s huge fireworks. But also you can’t quite trust anything she’s doing because for her art comes first always."

So who is the woman behind Kevin's sarcastic-yet-charming co-star and love interest? Montgomery has had a number of high-profile roles ranging from cult television shows like Salem and Entourage to acclaimed movies like Black Swan. Here are some of her most notable roles from the past few years.

Salem

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Montgomery plays Mary Sibley, a powerful (not to mention fashionable) witch who quite literally sold her soul to the devil with dark magic when her one true love John Alden (Shane West) went off to war and she found herself pregnant. The show, which debuted in 2014 on WGN America, started its third season on Nov. 2.

Downton Abbey

Every British actor needs a role on one of television's most popular period dramas. You might remember seeing Montgomery as Freda Dudley Ward, an English socialite, in the 2013 Christmas episode.

Entourage

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Montgomery played recurring character Jennie, Eric's British assistant, in the seventh and eighth seasons of the HBO.

Human Target

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Montgomery was a regular in the second season of FOX's Human Target. She played Ames, a thief so good at her job she could steal anything from anyone.

Merlin

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Montgomery played Princess Mithian, the love interest of King Arthur in Seasons 4 and 5 of the fantasy series.

Black Swan

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One of Montgomery's breakout roles came in Black Swan. Even though it was a small part — a girl named Madeline in the ballet company, who didn't quite understand everyone's hostility towards Portman's Swan Queen — she dazzled in the part.

Made In Jersey

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In the CBS drama, Montgomery played Martina Garretti, a Garden State native who is hired at a fancy Manhattan law firm and is unashamed of her true roots.

Hopefully, This Is Us will introduce Montgomery to even more viewers as her role continues to grow.

Images: Paul Drinkwater/NBC; PBS