BERLIN — When the director Paul Greengrass was gearing up to make his new film, “News of the World,” about a Civil War veteran in 1870s Texas who escorts an orphaned girl to her relatives across the state, he was anticipating one major challenge. “This is the first film I made with a child actor at the heart of it,” he said recently by phone.

The casting would be difficult on multiple levels, he realized. Although the character is onscreen for much of the movie, she has only a few lines of dialogue. Tom Hanks had already signed on as the lead, so she would have to go “toe to toe” with a superstar, Greengrass said. “It was a very, very hard ask.”

One of the first children he saw during the casting in 2019, however, was Helena Zengel, a then 11-year-old from Berlin with a tomboyish energy and platinum hair. “She was the only person I really had to look at,” he said. “It was the easiest decision in the film.”

“News of the World,” which opened Dec. 25 in theaters in the United States and Canada, and will be available on Netflix in other countries from February, is an international breakthrough for Zengel, who has already become one of the most talked-about actors — let alone child actors — to emerge in Germany in recent years.

She garnered widespread praise last year for her portrayal of a semi-feral 9-year-old in the movie “System Crasher,” which went on to be Germany’s official submission to the Academy Awards. That performance won her best actress this spring at the Lolas, Germany’s equivalent of the Oscars, making her the youngest recipient of that prize.

In “News of the World,” Zengel’s character, Johanna Leonberger, is left orphaned after her German parents are violently murdered on their farm when she is four. Taken in and raised by the Kiowa tribe, she is later removed by soldiers, and a traveling veteran, played by Hanks, agrees to bring her to a surviving aunt and uncle.

Zengel has received strong reviews for her performance, with critics praising her ability to imbue her defiant and alienated character with a sense of warmth and intelligence, and for channeling the emotional horrors of Johanna’s back story in near silence. Most of her lines are in Kiowa, a language she had to learn for the part.

Speaking via Zoom recently, Ms. Zengel was far gigglier and chattier — which is to say, far more like a regular 12-year-old — than her recent roles might suggest. She said that, like most children in Germany, she had spent most of this year at home, and that she was currently quarantined because classmates had tested positive for the coronavirus.

Before being cast in the film, she said, she had never heard of Hanks. “I think I’d seen the ‘Da Vinci Code’ before, but I didn’t know who he was,” she said. “I thought it was just some actor.”

In an email, Hanks praised Zengel’s skill of performing “with no buildup, no apprehension and no self-consciousness,” and said he wished he had “her same ease, her simplicity.”

Zengel said she had never taken an acting class, “because I’m not sure if there was much for me to learn.”

“I stand in front of the camera, I know what I want, and I do it,” she said, matter-of-factly.

This focus and willpower, her mother, Anne Zengel, explained, has been her daughter’s hallmark ever since she was a toddler. Her earliest forays into acting, at age 4, had emerged largely out of parental frustration, she said, because her daughter had “three times as much intensity” as other children and would act out if she was denied something she wanted.

“She had to function in society, so we had to figure out how to redirect her energy,” she said.

She enrolled Helena in ice-skating classes, and encouraged her to try acting. After a few small roles in German TV crime shows, as a bank robber’s daughter or a girl who falls from a bridge, she eventually landed a lead role in a German art-house film, “Dark Blue Girl,” at age 7.

“At some point, the thing happened that I hoped would happen,” her mother said. “She was actually valued for being so intense.”

In 2017, Zengel caught the attention of Nora Fingscheidt, the German director of “System Crasher,” a harrowing drama centered on a girl named Benni who is abused as a baby and abandoned by her mother, and who later lashes out at her caregivers and the society around her. The movie included a number of upsetting scenes, including of violence between children. In an interview, Fingscheidt said she needed a child actor who could convey Benni’s often terrifying physicality, while shouldering the psychological burden of the part.

She was struck by Zengel’s “cinematographic quality, with almost translucent white skin, white hair that make her look like an angel, but with an ambivalence that is fascinating,” she said. During the child actor’s audition, in which she was asked to improvise a scene in which she “freaks out” by screaming and throwing things, Fingscheidt said that she was drawn in by the way her “eyes sparkled when I told her she could behave as badly as she wanted.”

To help Zengel distinguish herself from her traumatized character, Fingscheidt said, the two would mime a little scene once shooting was over, with the director holding her hand like a shower head and the child actor pretending to wash underneath it, to indicate her transition back to herself. Zengel also wrote a journal, to help her process her feelings, the director added.

Zengel said the experience of making “System Crasher” helped her prepare for her role as Johanna, which she conceded was “not as extreme.”

Now Zengel is confronting the strange reality of international fame while being stuck at home, finishing seventh grade. This fall, Variety magazine selected her as one of its “actors to watch” and she said she had received offers for other roles in recent months, but that she was waiting until the pandemic subsided before making any decisions.

She said she was open to moving to the United States, though her mother said she was intent on her daughter having a normal childhood, and that she was comforted by Germany’s comparatively low-key celebrity culture.

“The thing about acting is that you just need to do it, and as long as you’re happy with it, then you’re doing it right,” Zengel said. “Also, it’s very fun to run around and scream.”