This Is Us season 4 opens with the introduction of a string of new actors and actresses joining the This is Us cast for the first time, along with all of the main cast members returning for the popular drama series as their respective characters.

After five months of waiting for fresh episodes, This Is Us finally returned on air with a special extended season 4 premiere. But while Jack (Milo Ventimiglia) and Rebecca (Mandy Moore) haven't been used too much thus far, the drama plans to devote more time to them and the Big Three throughout the season.

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Given the fact that This is Us has become a TV phenomenon and has already been renewed for two more seasons (after season 4), it makes sense that the producers are adding more people to the This is Us cast as well as characters to the lineup to keep the story going.

This Is Us Season 4's Returning Cast

This Is Us season 1

Milo Ventimiglia as Jack Pearson - The patriarch of the Pearson family and a Vietnam war veteran, Jack is the heart of the show. Often presented as the ideal family man, Jack had his personal demons, however, and fans are able to learn more about him thanks to the show's non-linear form of storytelling. Despite tragically dying almost two decades ago, his presence is felt throughout This Is Us as he continues to be a huge part of his wife and kids' present lives. Ventimiglia can be best remembered playing Jess Mariano in Gilmore Girls and Peter Petrelli in Heroes.

Mandy Moore as Rebecca Pearson - Jack's wife and the mother of the Big Three, Rebecca was an aspiring singer when she first met her husband. She walked away from her personal dreams and her affluent family and chose to live a quiet life with Jack and the kids. She's now married to Miguel - one of the lingering mysteries of the show. Fans remember Moore from her music in the 2000s. She also appeared in a few romantic films like A Walk To Remember (Jamie Sullivan) and How To Deal (Halley Martin).

Justin Hartley as Kevin Pearson - Technically the first born of the Pearson family, Kevin was a budding football player but he suffered a career-ending injury. He then focused his attention to acting, and is now transitioning to be a movie star. Like his father, Kevin is dealing with alcohol dependency issues. In the flash forward, fans know that he'll have a son of his own. Hartley played Green Arrow in Smallville and Adam Newmana in The Young and the Restless before joining This Is Us.

Chrissy Metz as Kate Pearson - The Pearsons' second-born and Kevin's twin sister, Kate has been dealing with weight issues her whole life. While she had a stellar relationship with her dad,   her dynamic with her mom has been more complicated - although they've been working on it recently. She's married to Toby, whom she shares a son with, Jack Jr. Metz mostly did guest roles in a series of TV shows, except American Horror Story: Freak Show where she played Barbara/Ima Wiggles for 5 episodes. She starred as Trish in Sierra Burgess Is A Loser and Joyce Smith in Breakthrough.

Sterling K. Brown as Randall Pearson - Jack and Rebecca's adopted son following the death of their third triplet, Randall is intellectually gifted, although he suffers from paralyzing anxiety. He's a former corporate man, who is now a politician after becoming a council man in Philadelphia. Randall is married to Beth, and together, they share two daughters, as well as an adopted one. Brown is best known for award-winning performance in American Crime Story: The People v. O.J. Simpson. He also played N'Jobu in Black Panther.

Chris Sullivan as Toby Damon - Kate's husband and the father of Jack Jr., Toby has had a traumatic childhood, and has also dealt with weight issues like his wife. While This Is Us never really shows Toby working, he's apparently an IT guy. Sullivan did a series of TV films before boarding the NBC drama. On the big screen, he was Taserface in Guardians of the Galaxy Vol. 2 and Brendan Looming in Live by Night.

Susan Kelechi Watson as Beth Pearson - Randall's wife and the mother of their kids, Beth was an aspiring ballet dancer, but circumstances forced her to leave her dreams behind. She was a stay-at-home mom before her husband haphazardly quit his job. Now, she's pursuing dance again by opening up a studio. Watson did several TV guesting in the past including short stints in Billions, The Blacklist and NCIS.

Jon Huertas as Miguel Rivas - An old friend of Jack, Miguel and his ex-wife were close to the Pearsons in the '80s. But in the aftermath of Jack's death, he and Rebecca got together and married. Huertas is known for playing Javier Esposito in Castle and Joe Negroni in the 1998 film Why Do Fools Fall in Love.

Eris Baker as Tess Pearson, Faithe Herman as Annie Pearson, and Lyric Ross as Deja - Tess and Annie are Randall and Beth's biological daughters. Deja, on the other hand, was adopted after her mother asked the Pearsons to take her in.

Girffin Dunne as Nick Pearson - Jack's estranged younger brother reconnected with the Pearsons back in season 3 after Kevin discovered that he's still alive. Aloof and snobbish, he asked his remaining family to leave him alone, but fans know he'll eventually come around and develop a relationship with them thanks to last season's flash forward scene. Dunne is a seasoned actor who appeared in Frasier, SNL and Law & Order: Criminal Intent. His movie credits include My Girl (Jake Bixler) and Dallas Buyers Club (Dr. Vass).

Related: This Is Us Theory: Why [SPOILER] Is In That Flashforward Scene

This Is Us Season 4's New Cast

Adult Jack in This Is Us

Jennifer Morrison as Cassidy Sharp - This Is Us' season 4 premiere debuts Cassidy Sharp - a military officer who was in active duty. But like Jack and Nicky, she suffers from PTSD and alcohol dependency from her deployment overseas. Fans will remember Morrison for her work in ABC's Once Upon A Time where she played Emma Swan. She also played Zoey Pierson for 13 episodes of How I Met Your Mother and Dr. Allison Cameron in House. On the big screen, she portrayed Winona Kirk in J.J. Abrams' Star Trek.

Tim Matheson as Dave Malone - The veteran actor stars as Rebecca's father in the season premiere for This Is Us. Not as snooty as Beck's mother, but he didn't waste any time to tell Jack and he doesn't want him for her daughter. Best known for playing Eric "Otter" Stratton in the film National Lampoon's Animal House, he also portrayed VP John Hoynes in The West Wing.

Asante Blackk as Malik - A young, single father living in the same community that Randall and his family moved to, Malik is trying to make sure that his daughter will have a great life. A love link between him and Deja was teased in the season premiere. Blackk is best known for his acclaimed work in When They See Us as Kevin Richardson.

Omar Epps as Darnell and Marsha Stephanie Blake as Kelly - Darnell and Kelly are Malik's parents who help him raise his daughter. Fans can expect eventual interaction between them and Randall's family as a relationship between their kids blossom. Epps has appeared in Scream 2 as Phil Stevens, as well as Dr. Dennis Gant in ER and Dr. Eric Foreman in House. Meanwhile. Blake co-starred with Blackk in When They See Us, her role as Linda McCray earned her a Primetime Emmy Award for Outstanding Supporting Actress in a Limited Series or Movie nomination.

Blake Stadnik as Adult Jack Damon - The first character introduced that exists in the far future, Kate and Toby's blind son, Jack, turned out just fine as he makes a name for himself as a singer. Stadnik, who lost majority of his eyesight due to Stargardt's disease, has previous appeared in Sweeney Todd and Les Miserables.

Auden Thornton as Lucy - Lucy is Jack's wife, who he met while waitressing at a diner, and she is kickstarting her career as a chef when she finds out that she's pregnant. Thornton is a Juilliard-graduate with roles in Beauty Mark, Arlington Road and True Story.

Nick Wechsler as Ryan Sharp - Cassidy's estranged husband, Ryan fully raises their son alone. Fans can remember Wechsler from his role as Kyle Valenti in Roswell and Jack Porter in Revenge.

Both Timothy Omundson and M. Night Shyamalan are tipped to star in This Is Us season 4 as well, but they have yet to appear in the series.

More: This Is Us: The 10 Best Characters, Ranked