12 Oppenheimer Actors You Didn't Realize Were Former Child Stars

If there's one thing that you can say about Christopher Nolan's "Oppenheimer," it's that the three-hour historical epic about the father of the atomic bomb boasts an incredibly deep bench. Nolan packs the film with well-known and well-liked actors, with many big names seemingly happy to sign on for little more than a cameo if it let them be part of "Oppenheimer." But aside from the Matt Damons and Kenneth Branaghs, there's also a surprising number of cast members who began their careers as child stars. 

Some came up during the mid-2000s golden age of the Disney Channel and Nickelodeon, while others date back decades earlier. Also, several have since gone on to lead well-developed and respected careers, while others are still in the process of proving themselves as adult actors in their own right. Whether they're child stars who audiences are surprised to see in grown-up roles, or actors they may not have even realized had careers in their childhood, "Oppenheimer" spares no expense in developing a roster of performers who got into the game at a very early age.

One of the most famous cast members of "Oppenheimer," Robert Downey Jr. plays incredibly against type as Lewis Strauss, shedding his affable Marvel stardom to portray a vindictive politician determined to bring down J. Robert Oppenheimer for a litany of perceived offenses. His performance ranks among the film's most acclaimed, and is seemingly poised to garner significant attention come awards season. And while the majority of audience members are familiar with Downey Jr.'s past output, few are likely aware that his roots in Hollywood stretch all the way back to his childhood.

Although Downey Jr. made a name for himself as a young adult actor in the mid-to-late 1980s, with performances in films like "Less Than Zero" and "Johnny Be Good," his career began when he was just a little boy making sporadic appearances in films directed by his father, Robert Downey Sr. His on-screen debut came in 1970 when, at just five years old, he essayed the role of Puppy in a quirky, experimental movie called "Pound."

While some of the other actors on this list are best known for their work as adults, Michael Angarano is probably equally well-remembered for his childhood performances. Angarano plays Robert Serber in "Oppenheimer," J. Robert Oppenheimer's colleague and close family friend. His role is not particularly large, but he features prominently in the sequences set during the Manhattan Project at Los Alamos.

Many audiences will likely recognize the adult version of Angarano — he has appeared in several high-profile projects, including "Minx," "Dollface," and an Emmy-nominated turn as Nick Pearson in "This Is Us." But the work he did as a child actor is also impressive. He was featured as the younger version of William in "Almost Famous," the surprise son of Jack in "Will & Grace," and a superhero-in-training in "Sky High." Millennials especially will remember his face from many of the most popular films and television shows of the late 1990s and early 2000s.

Scott Grimes might not be the biggest star in "Oppenheimer," but he's put together a prolific career as one of those character actors whose face you recognize but whose name you can never seem to remember. His role in the film is fairly small; he turns up as a council member during the Oppenheimer security hearing.

It's difficult to guess where fans might know Grimes from, and that's because he's appeared in so many different popular films and television series. He voices Steve Smith on "American Dad," for one. He also starred in Seth MacFarlane's "The Orville," enjoyed a 112-episode run on "ER," and featured prominently in the popular teen drama "Party of Five." His career began in 1984, when at the age of 13, he was cast in "A Doctor's Story." Just two years later, he landed a lead role in the horror comedy "Critters," which has since developed a cult following and spawned four sequels, although Grimes only returned for the first.

As the second son of famed Swedish actor Stellan Skarsgård, drama has always been in Gustaf Skarsgård's blood. Alongside several of his brothers (you may be familiar with Alexander and Bill), he has stepped out from his father's shadow and established himself as a talented performer in his own right. In "Oppenheimer," he assumes the role of Hans Bethe, a German-born physicist who toiled alongside Oppenheimer on the Manhattan Project, running the theoretical division of the program.

Skarsgård began his acting career at the age of nine, making an appearance in a 1989 Swedish film called "Codename Coq Rouge," which starred his father as a Swedish secret agent trying to prevent a terrorist attack. He acted sporadically in films throughout the 1990s, although his career began in earnest in the 2000s, when he was in his early 20s. After working in his native Sweden for many years, he made the jump to Hollywood, earning key roles in "Vikings," "Westworld," and "Cursed."

When looking for someone to play highly respected American physicist Seth Neddermeyer in "Oppenheimer," it's hard to imagine that Christopher Nolan's immediate thought was to recruit Rodrick from "Diary of a Wimpy Kid." But that's exactly what happened. Neddermeyer helps fill out the large ensemble cast at Los Alamos, and only eagle-eyed viewers will realize that he's played by former child actor Devon Bostick.

Born into a Canadian family entrenched in the entertainment industry — his mother is a casting director, while his father acts — Bostick landed his first credit at the age of seven in "Exhibit A: Secrets of Forensic Science." He worked continuously throughout his teen years, and went on to star in "Saw VI" and the first three films in the "Diary of a Wimpy Kid" franchise, where he played the main character's older brother. Since then, he's successfully transitioned into a career as an adult actor, appearing in "Okja," "The 100," "The Marvelous Mrs. Maisel," and "FUBAR."

Since her teen years, Emma Dumont has enjoyed success not just as an actress, but also as a model and a dancer. These talents helped her land one of the biggest roles of her career, starring in the short-lived but generally well-liked ABC Family drama "Bunheads," about a group of young ballet students and their teacher (played by Broadway stalwart Sutton Foster). In "Oppenheimer," she shows up briefly as Jackie Oppenheimer, the girlfriend and later wife of Frank Oppenheimer (Robert's younger brother), whose links to the Communist Party only add to the troubles faced by Oppie in his government security hearing.

Dumont made her Hollywood debut in 2009, when she was just 15 years old. She landed roles in two films that year: "True Adolescents," an indie dramedy starring Mark Duplass, and "Dear Lemon Lima," about a group of teenage girls attending a prep school in Alaska. Since then, she has steadily taken on higher-profile projects in both films and on television, including key roles in "Aquarius" and "The Gifted," as well as smaller turns in "Inherent Vice" and "Licorice Pizza."