James Cameron marvels at Sigourney Weaver’s transformation into a teen for Avatar: Fire and Ash

James Cameron is still in awe of Sigourney Weaver’s performance in the upcoming Avatar: Fire and Ash, where the 76-year-old actress plays Kiri, a 14-year-old Na’vi teenager. Speaking about the role, Cameron said Weaver’s transformation was astonishing to witness during filming and unlike anything he had seen before.

“She became a different person,” Cameron said. “She was lighter, she was younger, she was more open.” He added that watching Weaver slip so completely into the mindset of a teenager was “one of the biggest acting challenges” he’s ever seen an actor take on and successfully pull off.

Cameron explained that Weaver was able to access her own memories of adolescence to ground the performance in emotional truth. “She was able to remember what it felt like to be awkward, uncertain and searching,” he said. “That vulnerability is very hard to fake, and she didn’t fake it. She lived it.”

Weaver herself described the role as unexpectedly personal. Reflecting on playing a teenager again, she said, “It was actually very therapeutic to go back and visit that time in my life.”

She added that tapping into those emotions helped her connect deeply with Kiri’s inner world, particularly the character’s sense of being different and struggling to understand her place.

Kiri is the daughter of Dr. Grace Augustine’s Na’vi avatar and continues to be a central emotional anchor within the Avatar saga. Cameron emphasised that Weaver’s performance gives the film much of its heart, saying, “Kiri is searching, questioning, feeling everything very intensely and Sigourney captured that perfectly.”

Avatar: Fire and Ash, set for release on December 19, 2025, continues the story of the Sully family as they face new dangers and evolving relationships on Pandora.

Cameron believes Weaver’s work will once again surprise audiences, proving that age is no barrier to authenticity when it comes to powerful storytelling.

“I’ve worked with Sigourney for decades,” Cameron said, “and I’ve never seen her do anything quite like this.”